Removed leftover variable (#4275)

* Removed an unused variable.
Thanks to @pigati23!

src/map/skill.cpp

@@ -1157,7 +1157,6 @@ int skill_additional_effect(struct block_list* src, struct block_list *bl, uint1
 	struct mob_data *md, *dstmd;
 	struct status_data *sstatus, *tstatus;
 	struct status_change *sc, *tsc;
-	enum sc_type status;
 	int skill;
 	int rate;