I have checked in the patch to clean up after GCC's change to version number handling. This should address all reported issues with build, installation, etc. Per Ian's suggestion, I am doing a multilib-ful build with a relative $(srcdir), which may expose more problems, which will be addressed in a follow-up.
It is now safe again to modify configure scripts in the gcc repository; you should not encounter missing .m4 files. I have not audited the src repository for problematic constructs. The odds are low that any problems exist, since the affected macros and variables all have to do with passing information from the gcc subdirectory to runtime library directories, but just for the record: TL_AC_GCC_VERSION no longer exists, and TL_AC_GXX_INCLUDE_DIR has changed semantics. Also, the top level Makefile no longer passes down certain variables: libsubdir, libstdcxx_incdir, gxx_include_dir, gcc_version, gcc_version_full, and gcc_version_trigger. I would like to take this opportunity to encourage the libjava, libffi, and libstdc++ maintainers to convert to nonrecursive Makefiles. (In other words, just one Makefile.am/Makefile.in pair at the top level of your subdirectory; perhaps with included fragments in lower-level subdirectories.) zw
