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

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>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43669 3c298f89-4303-0410-b956-a3cf2f4a3e73