Log Message:
lang/gnat-aux: Sync with gcc 4.6.3

GCC 4.6.3 was released 01 MAR 2012.  It is a bug-fix release for regressions
and serious bugs.  Seventy-four bug reports were addressed.  The link is
available at bottom of http://gcc.gnu.org/gcc-4.6/changes.html

Unlike release 4.6.2, a few Ada issues were among those addressed.