Remove bcopy(), bzero(), bcmp()

bcopy() has a confusing argument order and is actually a move, not a
copy; they're all deprecated since POSIX.1-2001 and removed in -2008,
and we shim them out to mem*() on Linux anyway

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12996

module/zfs/vdev_label.c

@@ -1565,7 +1565,7 @@ vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
 	ASSERT(ub);
 	ASSERT(config);
 
-	bzero(ub, sizeof (uberblock_t));
+	memset(ub, 0, sizeof (uberblock_t));
 	*config = NULL;
 
 	cb.ubl_ubbest = ub;