Fall back to opaque sprite if no formats with alpha are supported.

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403835

test/testsprite2.c

@@ -81,6 +81,10 @@ LoadSprite(char *file)
     for (i = 0; i < state->num_windows; ++i) {
         SDL_SelectRenderer(state->windows[i]);
         sprites[i] = SDL_CreateTextureFromSurface(0, temp);
+        if (!sprites[i]) {
+		SDL_SetColorKey(temp, 0, 0);
+		sprites[i] = SDL_CreateTextureFromSurface(0, temp);
+	}
         if (!sprites[i]) {
             fprintf(stderr, "Couldn't create texture: %s\n", SDL_GetError());
             SDL_FreeSurface(temp);