xfs: mark the record passed into xchk_btree functions as const

xchk_btree calls a user-supplied function to validate each btree record
that it finds.  Those functions are not supposed to change the record
data, so mark the parameter const.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_bmap_btree.c

@@ -58,7 +58,7 @@ xfs_bmdr_to_bmbt(
 
 void
 xfs_bmbt_disk_get_all(
-	struct xfs_bmbt_rec	*rec,
+	const struct xfs_bmbt_rec *rec,
 	struct xfs_bmbt_irec	*irec)
 {
 	uint64_t		l0 = get_unaligned_be64(&rec->l0);