xfs/006 has no requirements that are specific to XFS, so make it generic
and other filesystems could get some coverage too.
Along with the movement, I also added a test that removes all created
dirs, as that's how the original bug was found.
Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>