Use C++11's in-line member initializers instead of default constructors with initializer lists, for some structs.

--HG--
branch : minor

src/modules/window/sdl/Window.h

@@ -111,10 +111,8 @@ private:
 
 	struct _currentMode
 	{
-		_currentMode();
-
-		int width;
-		int height;
+		int width  = 800;
+		int height = 600;
 		WindowSettings settings;
 		Object::StrongRef<love::image::ImageData> icon;