main: SDL_AppQuit() now reports the result value.

Fixes #10994.

examples/audio/02-simple-playback-callback/simple-playback-callback.c

@@ -104,7 +104,7 @@ SDL_AppResult SDL_AppIterate(void *appstate)
 }
 
 /* This function runs once at shutdown. */
-void SDL_AppQuit(void *appstate)
+void SDL_AppQuit(void *appstate, SDL_AppResult result)
 {
     /* SDL will clean up the window/renderer for us. */
 }