Slave aggro (fixes #1676)

- Slaves will now become aggressive when their master starts chasing a target to attack it

src/map/mob.c

@@ -1344,7 +1344,9 @@ static int mob_ai_sub_hard_slavemob(struct mob_data *md,unsigned int tick)
 		if (ud) {
 			struct block_list *tbl=NULL;
 			if (ud->target && ud->state.attack_continue)
-				tbl=map_id2bl(ud->target);
+				tbl = map_id2bl(ud->target);
+			else if (ud->target_to && ud->state.attack_continue)
+				tbl = map_id2bl(ud->target_to);
 			else if (ud->skilltarget) {
 				tbl = map_id2bl(ud->skilltarget);
 				//Required check as skilltarget is not always an enemy. [Skotlex]