Add a new macro, XFS_IS_CORRUPT, which we will use to integrate some
corruption reporting when the corruption test expression is true.  This
will be used in the next patch to remove the ugly XFS_WANT_CORRUPT*
macros.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>