Log Message:
graphics/xart: Fix post-extract chmod again

Three months ago, the post-extract command was modified because it didn't
work on Solaris.  The fix provided broke the non-root user build.  The
problem with the original post-extract command was that it started with
$WRKDIR instead of $WRKSRC.  Return this target back to a tweaked version
of the original post-extract command (and cross fingers that it still
works on Solaris)