xfs: add scrub cross-referencing helpers for the refcount btrees

Source kernel commit: 49db55eca5665e32c9d3e67a7d5694bcc6c274de

Add a couple of functions to the refcount btrees that will be used
to cross-reference metadata against the refcountbt.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

2 files changed