gcc: don't clobber stamp-bits with a symlink to itself

Several versions of gcc have an issue in libstdc++v3 where the build may
clobber stamp-bits with a link to itself.  This doesn't manifest itself
on all systems.  On several Ubuntu systems, this doesn't appear to be a
problem, but it is an issue on Fedora 16 systems.

To fix the issue, we'll simply filter out stamp-bits from the symlinks
to be generated.

Note: gcc 4.4.7 is unaffected by this issue, so no fix is necessary
there.

Signed-off-by: John Szakmeister <john@szakmeister.net>

SVN-Revision: 43669