Fix c++11 narrowing error

    src/video/mng.cpp:301:20: error: non-constant-expression cannot be narrowed from type 'int' to 'Sint16' (aka 'short') in initializer list [-Wc++11-narrowing]
                    SDL_Rect rect = {x, y, surface->w, surface->h};
                                     ^

Author: AMDmi3

src/video/mng.cpp

@@ -298,7 +298,7 @@ void Mng::Draw(int x, int y)
 	} else
 #endif
 	{
-		SDL_Rect rect = {x, y, surface->w, surface->h};
+		SDL_Rect rect = {(Sint16)x, (Sint16)y, (Uint16)surface->w, (Uint16)surface->h};
 		SDL_BlitSurface(surface, NULL, TheScreen, &rect);
 	}
 }