xfs_scrub: don't try any file repairs during phase 3 if AG metadata bad

xfs_scrub: don't try any file repairs during phase 3 if AG metadata bad

Currently, phase 3 tries to repair file metadata even after phase 2
tells us that there are problems with the AG metadata.  While this
generally won't cause too many problems since the repair code will bail
out on any obvious corruptions it finds, this isn't totally foolproof.
If the filesystem space metadata are not in good shape, we want to queue
the file repairs to run /after/ the space metadata repairs in phase 4.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>