Add SDL_RenderGetWindow() API to get the window associated with a renderer (#5440)

Add SDL_RenderGetWindow() API to get the window associated with a renderer

include/SDL_render.h

@@ -261,6 +261,15 @@ extern DECLSPEC SDL_Renderer * SDLCALL SDL_CreateSoftwareRenderer(SDL_Surface *
  */
 extern DECLSPEC SDL_Renderer * SDLCALL SDL_GetRenderer(SDL_Window * window);
 
+/**
+ * Get the window associated with a renderer.
+ *
+ * \param renderer the renderer to query
+ * \returns the window on success or NULL on failure; call
+ *          SDL_GetError() for more information.
+ */
+extern DECLSPEC SDL_Window * SDLCALL SDL_RenderGetWindow(SDL_Renderer *renderer);
+
 /**
  * Get information about a rendering context.
  *