Properly clean up SDL in example

Author: sharkwouter

_includes/samples/sdl2/main.c

@@ -51,6 +51,8 @@ int main(int argc, char *argv[])
         SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
         SDL_RenderPresent(renderer);
     }
+    SDL_DestroyRenderer(renderer);
+    SDL_DestroyWindow(window);
     SDL_Quit();
 
     return 0;