Update to GCC 4.7.2

  GCC 4.7.2 is the first bug-fix release containing important fixes
  for regressions and serious bugs in GCC 4.7.1 with over 70 bugs
  fixed since the previous release.

  A notable change in GCC 4.7.2 compared to 4.7.1 are ABI bug fixes
  related to some C++11 templates (std::list and std::pair).  As a result,
  code using those templates in C++11 mode is again ABI compatible with
  code in C++03/C++98 mode or C++11 mode of GCC 4.6 and earlier, but might
  be ABI incompatible with code compiled by GCC 4.7.1 or 4.7.0 in C++11
  mode.  See http://gcc.gnu.org/gcc-4.7/changes.html for more details.

  This is the list of problem reports (PRs) from GCC's bug tracking system
  that are known to be fixed in this release. This list might not be complete
  (that is, it is possible that some PRs that have been fixed are not listed
  here).
  http://gcc.gnu.org/bugzilla/buglist.cgi?bug_status=RESOLVED&resolution=FIXED&target_milestone=4.7.2

(sbd)