Log message:
Set BUILDLINK_ABI_DEPENDS correctly (with +=, not ?=)
It turns out there were a lot of these.

Log message:
Fix PLIST on !Linux

Log message:
Make gcc-inplace-math work with new mpfr.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51935

Log message:
Disable GC_register_my_thread and GC_unregister_my_thread on NetBSD as
the version of boehm-gc bundled with gcc does not support NetBSD threads.

Log message:
Remove gcc-go from PKG_SUGGESTED_OPTIONS as it seems to have some build
problems.

Log message:
Improve the patch that adds the %M spec string to handle multilib_os_dir
being NULL.

When building a single ABI capable gcc (e.g. 32bit systems), multilib_os_dir
may be NULL and this would cause gcc to segfault when trying to link libgcc.

Thanks to Filip Hajny for isolating the problem to the %M patch.

Log message:
Fix typo.

Log message:
The 'gcc-objc++' should enable both the 'gcc-c++' and 'gcc-objc' options.

Log message:
Change the way that ${MULTILIB_SUPPORTED} is used.

Three situations need it be handled:

1) Multilib support is unknowen, i.e. there is nothing in the options.mk
   file to appropriately set ${MULTILIB_SUPPORTED} (currently all platforms
   except Linux/x86_64).  In this situation nothing should be done.

2) Multilib _is_ supported, in this situation the 'gcc-multilib' option
   should be made available and the CONFIGURE_ARGS modified accordingly.

3) Multilib _is not_ supported, in this situation CONFIGURE_ARGS need to
   be modified.

Log message:
fixes malformed conditional with MULTILIB_SUPPORTED.