The files /etc/pam.d/common-* are generated by the script /usr/sbin/pam-auth-update; any time you regenerate the pam.<distro>.txt recipe, you will have to add those files back to recipe file.
xserver-bin.
<distro>
.txt
The startx script uses options for mktemp that are not supported by busybox's version of mktemp. A copy of the startx script has been modified and placed in :BUILD_BASE:/common/scripts for other projects to pick up and use.