fixed a warning

src/server/scripts/Northrend/IcecrownCitadel/instance_icecrown_citadel.cpp

@@ -141,7 +141,7 @@ class instance_icecrown_citadel : public InstanceMapScript
                 }
             }
 
-            void OnPlayerEnter(Player* player) override
+            void OnPlayerEnter(Player* /*player*/) override
             {
                 if (GetBossState(DATA_LADY_DEATHWHISPER) == DONE && GetBossState(DATA_ICECROWN_GUNSHIP_BATTLE) != DONE)
                     SpawnGunship();