common/rc: let xfs_scrub tell us about its unicode checker

common/rc: let xfs_scrub tell us about its unicode checker

Now that xfs_scrub can report whether or not it was built with the
Unicode name checker, rewrite _check_xfs_scrub_does_unicode to take
advantage of that.  This supersedes the old method of trying to observe
dynamic library linkages and grepping the binary, neither of which
worked very well.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>