main: SDL_AppQuit() now reports the result value.

Fixes #10994.

test/testgpu_simple_clear.c

@@ -110,7 +110,7 @@ SDL_AppResult SDL_AppIterate(void *appstate)
     return SDL_APP_CONTINUE;
 }
 
-void SDL_AppQuit(void *appstate)
+void SDL_AppQuit(void *appstate, SDL_AppResult result)
 {
     /* Print out some timing information */
     const Uint64 now = SDL_GetTicks();