remove dead IVictoryConditions interface

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -163,7 +163,6 @@ namespace OpenRA.Traits
 	public interface IRenderOverlay { void Render(); }
 	public interface INotifyIdle { void Idle(Actor self); }
 
-	public interface IVictoryConditions { }
 	public interface IBlocksBullets { }
 
 	public interface IRenderSelection { void Render(Actor self); }