Fixes Cross Impact on GvG and Battleground maps (#5823)

* Fixes #5775.
* Cross Impact is now usable on GvG and Battleground map types.
Thanks to @mazvi!

src/map/skill.cpp

@@ -5682,7 +5682,7 @@ int skill_castend_damage_id (struct block_list* src, struct block_list *bl, uint
 		}
 		break;
 	case GC_CROSSIMPACT:
-		if (skill_check_unit_movepos(5, src, bl->x, bl->y, 1, 1)) {
+		if (skill_check_unit_movepos(0, src, bl->x, bl->y, 1, 1)) {
 			skill_blown(src, src, 1, (map_calc_dir(bl, src->x, src->y) + 4) % 8, BLOWN_IGNORE_NO_KNOCKBACK); // Target position is actually one cell next to the target
 			skill_attack(BF_WEAPON, src, src, bl, skill_id, skill_lv, tick, flag);
 		} else {