Attempt to fix MSVC compilation

client/battle/CBattleObstacleController.h

@@ -16,7 +16,7 @@ class IImage;
 class CCanvas;
 class CAnimation;
 class CBattleInterface;
-class CObstacleInstance;
+struct CObstacleInstance;
 struct Point;
 
 class CBattleObstacleController

client/battle/CBattleStacksController.h

@@ -15,8 +15,8 @@ struct BattleObjectsByHex;
 struct SDL_Surface;
 struct BattleHex;
 struct StackAttackedInfo;
-struct BattleAction;
 
+class BattleAction;
 class CCanvas;
 class SpellID;
 class CBattleInterface;