module: zfs: multilist: shim out multilist_d2l()

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12844

module/zfs/multilist.c

@@ -36,6 +36,8 @@ multilist_d2l(multilist_t *ml, void *obj)
 {
 	return ((multilist_node_t *)((char *)obj + ml->ml_offset));
 }
+#else
+#define	multilist_d2l(ml, obj) ((void) sizeof (ml), (void) sizeof (obj), NULL)
 #endif
 
 /*