I just had a patch accepted to GCC! gcc/ada/init.c, r195862.
2013-02-07 Simon Wright <simon@pushface.org>
PR target/50678
* init.c (__darwin_major_version): New function for x86-64/Darwin.
(__gnat_adjust_context_for_raise) [Darwin]: Disable the workaround
on Darwin 12 and above.