deps: SDL update to 2.30.0 (#3384)

In the hopes that some things have been fixed in the last year
(GAME_CONTROLLER init time, etc)

Make sure this does not regress #2691

third-party/SDL/Xcode-iOS/Demos/src/touch.c

@@ -57,7 +57,7 @@ initializeTexture(SDL_Renderer *renderer)
 {
     SDL_Surface *bmp_surface;
     bmp_surface = SDL_LoadBMP("stroke.bmp");
-    if (bmp_surface == NULL) {
+    if (!bmp_surface) {
         fatalError("could not load stroke.bmp");
     }
     brush =