examples: Use SDL_Log() instead of message boxes for errors.

Fixes #11094.

examples/renderer/04-points/points.c

@@ -37,12 +37,12 @@ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
     int i;
 
     if (!SDL_Init(SDL_INIT_VIDEO)) {
-        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't initialize SDL!", SDL_GetError(), NULL);
+        SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
         return SDL_APP_FAILURE;
     }
 
     if (!SDL_CreateWindowAndRenderer("examples/renderer/points", WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer)) {
-        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create window/renderer!", SDL_GetError(), NULL);
+        SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
         return SDL_APP_FAILURE;
     }