Add revision to the 9.1.7 version of mesa thats +1 higher than
currently in ports.
Make sure to test WITH_NEW_MESA _after_ bsd.mesalib.mk is included
so bsd.mesalib.mk can set it.


git-svn-id: https://trillian.chruetertee.ch/svn/ports/branches/experimental@1527 058c260c-8361-11dd-a0ac-aa2bafec7d09