[SDL2] pointer boolean (#8523)

Xcode-iOS/Demos/src/rectangles.c

@@ -58,11 +58,11 @@ main(int argc, char *argv[])
 
     /* create window and renderer */
     window = SDL_CreateWindow(NULL, 0, 0, 320, 480, SDL_WINDOW_ALLOW_HIGHDPI);
-    if (window == NULL) {
+    if (!window) {
         fatalError("Could not initialize Window");
     }
     renderer = SDL_CreateRenderer(window, -1, 0);
-    if (renderer == NULL) {
+    if (!renderer) {
         fatalError("Could not create renderer");
     }