Fixed script command unitkill crashing the server (fixes #1027)

* Resolves an issue with Mercenary causing the server to crash when killed through the script command unitkill.
* Blame dd67f9d.

src/map/mercenary.c

@@ -417,12 +417,13 @@ void mercenary_heal(struct mercenary_data *md, int hp, int sp) {
 }
 
 /**
-* Delete Mercenary
-* @param md Mercenary
-**/
+ * Delete Mercenary
+ * @param md: Mercenary
+ * @return false for status_damage
+ */
 bool mercenary_dead(struct mercenary_data *md) {
 	mercenary_delete(md, 1);
-	return true;
+	return false;
 }
 
 /**