xfs_scrub: handle totally empty inode chunks

xfs_scrub: handle totally empty inode chunks

We try to load a single inobt record with each FSINUMBERS call.  If the
chunk is totally empty (which can happen when there are more than one
inobt record per block) we should skip to the next INUMBERS call since
there are no inodes to bulkstat.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>