Add instructions on how to generate the configure script.

…n_methods

Useful Span-based methods for ByteString

…t_objc_class_prefix

objective-c: Add `objc_class_prefix` generation option.

We would like for upb_Map_Delete() to optionally return the deleted value.
Unfortunately this will require several steps since we are crossing repos.
Step #4: update PHP/Ruby and advance the upb version used by protobuf

PiperOrigin-RevId: 498406089

We would like for upb_Map_Delete() to optionally return the deleted value.
Unfortunately this will require several steps since we are crossing repos.
Step #4: update PHP/Ruby and advance the upb version used by protobuf

PiperOrigin-RevId: 498406089

We would like for upb_Map_Delete() to optionally return the deleted value.
Unfortunately this will require several steps since we are crossing repos.
Step #4: update PHP/Ruby and advance the upb version used by protobuf

PiperOrigin-RevId: 498406089

We would like for upb_Map_Delete() to optionally return the deleted value.
Unfortunately this will require several steps since we are crossing repos.
Step #4: advance the upb version used by protobuf and update PHP/Ruby accordingly.

PiperOrigin-RevId: 498406089

We would like for upb_Map_Delete() to optionally return the deleted value.
Unfortunately this will require several steps since we are crossing repos.
Step #4: advance the upb version used by protobuf and update PHP/Ruby accordingly.

PiperOrigin-RevId: 498406089

We would like for upb_Map_Delete() to optionally return the deleted value.
Unfortunately this will require several steps since we are crossing repos.
Step #4: advance the upb version used by protobuf and update PHP/Ruby accordingly.

PiperOrigin-RevId: 498426185

==500166==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0xdd383e in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7
    #1 0xdd1eb2 in google::protobuf::compiler::DiskSourceTree::DiskFileToVirtualFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:431:51
    #2 0x540619 in google::protobuf::compiler::CommandLineInterface::MakeProtoProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1362:24
    #3 0x5314fb in google::protobuf::compiler::CommandLineInterface::MakeInputsBeProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1415:10
    #4 0x5314fb in google::protobuf::compiler::CommandLineInterface::InitializeDiskSourceTree(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1168:8
    #5 0x52541f in google::protobuf::compiler::CommandLineInterface::Run(int, char const* const*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1026:10
    protocolbuffers#6 0x50f5d6 in google::protobuf::compiler::ProtobufMain(int, char**) build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:104:14
    protocolbuffers#7 0x50fe58 in main build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:112:10
    protocolbuffers#8 0x7f817143db24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    protocolbuffers#9 0x48904d in _start (/mnt/ch/ClickHouse/build_msan/contrib/protobuf-cmake/protoc+0x48904d)

  Uninitialized value was created by an allocation of 'sb' in the stack frame of function '_ZN6google8protobuf8compiler14DiskSourceTree12OpenDiskFileERKNSt3__112basic_stringIcNS3_11char_traitsIcEENS3_9allocatorIcEEEE'
    #0 0xdd3320 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:492

SUMMARY: MemorySanitizer: use-of-uninitialized-value build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)
Exiting

This fixes an MSAN warning of the form:

```
WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x7fc964f2a597 in arena_findroot third_party/upb/upb/mem/arena.c:64:3
    #1 0x7fc964f2a597 in upb_Arena_Free third_party/upb/upb/mem/arena.c:211:7
    protocolbuffers#2 0x7fc9d2af0028 in std::__msan::unique_ptr<upb_Arena, void (*)(upb_Arena*)>::~unique_ptr() third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/__memory/unique_ptr.h:277:7
    protocolbuffers#3 0x7fc9d2aef7a2 in ~Arena third_party/upb/upb/upb.hpp:70:7
    protocolbuffers#4 0x7fc9d2aef7a2 in ~InlinedArena third_party/upb/upb/upb.hpp:97:7
    protocolbuffers#5 0x7fc9d2aef7a2 in Cpp_InlinedArena2_Test::TestBody() third_party/upb/upb/test/test_cpp.cc:187:1
    protocolbuffers#6 0x7fc97da78a57 in testing::Test::Run() third_party/googletest/googletest/src/gtest.cc:2695:5
    protocolbuffers#7 0x7fc97da7a3e8 in testing::TestInfo::Run() third_party/googletest/googletest/src/gtest.cc:2844:11
    protocolbuffers#8 0x7fc97da7b897 in testing::TestSuite::Run() third_party/googletest/googletest/src/gtest.cc:3003:30
    protocolbuffers#9 0x7fc97daa5136 in testing::internal::UnitTestImpl::RunAllTests() third_party/googletest/googletest/src/gtest.cc:5899:44
    protocolbuffers#10 0x7fc97daa455c in HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> third_party/googletest/googletest/src/gtest.cc
    protocolbuffers#11 0x7fc97daa455c in testing::UnitTest::Run() third_party/googletest/googletest/src/gtest.cc:5464:10
    protocolbuffers#12 0x562a7fb876f0 in RUN_ALL_TESTS third_party/googletest/googletest/include/gtest/gtest.h:2329:73
    protocolbuffers#13 0x562a7fb876f0 in main testing/base/internal/gunit_main.cc:86:10
    protocolbuffers#14 0x7fc9ba9b7632 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x61632) (BuildId: 280088eab084c30a3992a9bce5c35b44)
    protocolbuffers#15 0x562a7fafdbe9 in _start /build/work/ab393f4ac612f9027aae6b1a7226027ba2a2/google3/blaze-out/k8-opt/bin/third_party/grte/v5_src/grte-scratch/BUILD/src/csu/../sysdeps/x86_64/start.S:120

  Member fields were destroyed
    #0 0x562a7fb0b13d in __sanitizer_dtor_callback_fields third_party/llvm/llvm-project/compiler-rt/lib/msan/msan_interceptors.cpp:960:5
    #1 0x7fc9d2aef79a in ~InlinedArena third_party/upb/upb/upb.hpp:105:8
    protocolbuffers#2 0x7fc9d2aef79a in ~InlinedArena third_party/upb/upb/upb.hpp:97:7
    protocolbuffers#3 0x7fc9d2aef79a in Cpp_InlinedArena2_Test::TestBody() third_party/upb/upb/test/test_cpp.cc:187:1
    protocolbuffers#4 0x7fc97da78a57 in testing::Test::Run() third_party/googletest/googletest/src/gtest.cc:2695:5
    protocolbuffers#5 0x7fc97da7a3e8 in testing::TestInfo::Run() third_party/googletest/googletest/src/gtest.cc:2844:11
    protocolbuffers#6 0x7fc97da7b897 in testing::TestSuite::Run() third_party/googletest/googletest/src/gtest.cc:3003:30
    protocolbuffers#7 0x7fc97daa5136 in testing::internal::UnitTestImpl::RunAllTests() third_party/googletest/googletest/src/gtest.cc:5899:44
    protocolbuffers#8 0x7fc97daa455c in HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool> third_party/googletest/googletest/src/gtest.cc
    protocolbuffers#9 0x7fc97daa455c in testing::UnitTest::Run() third_party/googletest/googletest/src/gtest.cc:5464:10
    protocolbuffers#10 0x562a7fb876f0 in RUN_ALL_TESTS third_party/googletest/googletest/include/gtest/gtest.h:2329:73
    protocolbuffers#11 0x562a7fb876f0 in main testing/base/internal/gunit_main.cc:86:10
    protocolbuffers#12 0x7fc9ba9b7632 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x61632) (BuildId: 280088eab084c30a3992a9bce5c35b44)
    protocolbuffers#13 0x562a7fafdbe9 in _start /build/work/ab393f4ac612f9027aae6b1a7226027ba2a2/google3/blaze-out/k8-opt/bin/third_party/grte/v5_src/grte-scratch/BUILD/src/csu/../sysdeps/x86_64/start.S:120
```

PiperOrigin-RevId: 511849224

PiperOrigin-RevId: 573375093

PiperOrigin-RevId: 573375093

PiperOrigin-RevId: 574544964

==500166==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0xdd383e in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7
    #1 0xdd1eb2 in google::protobuf::compiler::DiskSourceTree::DiskFileToVirtualFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:431:51
    #2 0x540619 in google::protobuf::compiler::CommandLineInterface::MakeProtoProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1362:24
    #3 0x5314fb in google::protobuf::compiler::CommandLineInterface::MakeInputsBeProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1415:10
    #4 0x5314fb in google::protobuf::compiler::CommandLineInterface::InitializeDiskSourceTree(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1168:8
    #5 0x52541f in google::protobuf::compiler::CommandLineInterface::Run(int, char const* const*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1026:10
    protocolbuffers#6 0x50f5d6 in google::protobuf::compiler::ProtobufMain(int, char**) build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:104:14
    protocolbuffers#7 0x50fe58 in main build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:112:10
    protocolbuffers#8 0x7f817143db24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    protocolbuffers#9 0x48904d in _start (/mnt/ch/ClickHouse/build_msan/contrib/protobuf-cmake/protoc+0x48904d)

  Uninitialized value was created by an allocation of 'sb' in the stack frame of function '_ZN6google8protobuf8compiler14DiskSourceTree12OpenDiskFileERKNSt3__112basic_stringIcNS3_11char_traitsIcEENS3_9allocatorIcEEEE'
    #0 0xdd3320 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:492

SUMMARY: MemorySanitizer: use-of-uninitialized-value build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)
Exiting

==500166==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0xdd383e in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7
    #1 0xdd1eb2 in google::protobuf::compiler::DiskSourceTree::DiskFileToVirtualFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:431:51
    #2 0x540619 in google::protobuf::compiler::CommandLineInterface::MakeProtoProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1362:24
    #3 0x5314fb in google::protobuf::compiler::CommandLineInterface::MakeInputsBeProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1415:10
    #4 0x5314fb in google::protobuf::compiler::CommandLineInterface::InitializeDiskSourceTree(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1168:8
    #5 0x52541f in google::protobuf::compiler::CommandLineInterface::Run(int, char const* const*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1026:10
    protocolbuffers#6 0x50f5d6 in google::protobuf::compiler::ProtobufMain(int, char**) build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:104:14
    protocolbuffers#7 0x50fe58 in main build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:112:10
    protocolbuffers#8 0x7f817143db24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    protocolbuffers#9 0x48904d in _start (/mnt/ch/ClickHouse/build_msan/contrib/protobuf-cmake/protoc+0x48904d)

  Uninitialized value was created by an allocation of 'sb' in the stack frame of function '_ZN6google8protobuf8compiler14DiskSourceTree12OpenDiskFileERKNSt3__112basic_stringIcNS3_11char_traitsIcEENS3_9allocatorIcEEEE'
    #0 0xdd3320 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:492

SUMMARY: MemorySanitizer: use-of-uninitialized-value build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)
Exiting

==500166==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0xdd383e in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7
    #1 0xdd1eb2 in google::protobuf::compiler::DiskSourceTree::DiskFileToVirtualFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:431:51
    #2 0x540619 in google::protobuf::compiler::CommandLineInterface::MakeProtoProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1362:24
    #3 0x5314fb in google::protobuf::compiler::CommandLineInterface::MakeInputsBeProtoPathRelative(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1415:10
    #4 0x5314fb in google::protobuf::compiler::CommandLineInterface::InitializeDiskSourceTree(google::protobuf::compiler::DiskSourceTree*, google::protobuf::DescriptorDatabase*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1168:8
    #5 0x52541f in google::protobuf::compiler::CommandLineInterface::Run(int, char const* const*) build_msan/./contrib/protobuf/src/google/protobuf/compiler/command_line_interface.cc:1026:10
    protocolbuffers#6 0x50f5d6 in google::protobuf::compiler::ProtobufMain(int, char**) build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:104:14
    protocolbuffers#7 0x50fe58 in main build_msan/./contrib/protobuf/src/google/protobuf/compiler/main.cc:112:10
    protocolbuffers#8 0x7f817143db24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    protocolbuffers#9 0x48904d in _start (/mnt/ch/ClickHouse/build_msan/contrib/protobuf-cmake/protoc+0x48904d)

  Uninitialized value was created by an allocation of 'sb' in the stack frame of function '_ZN6google8protobuf8compiler14DiskSourceTree12OpenDiskFileERKNSt3__112basic_stringIcNS3_11char_traitsIcEENS3_9allocatorIcEEEE'
    #0 0xdd3320 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:492

SUMMARY: MemorySanitizer: use-of-uninitialized-value build_msan/./contrib/protobuf/src/google/protobuf/compiler/importer.cc:504:7 in google::protobuf::compiler::DiskSourceTree::OpenDiskFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)
Exiting