WIP: testing usage of SDL renderer

It does segfault.

src/main.c

@@ -125,6 +125,9 @@ int main(int argc, char **argv) {
   window = SDL_CreateWindow(
     "", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, dm.w * 0.8, dm.h * 0.8,
     SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_HIDDEN);
+
+  fprintf(stderr, "New window: %p\n", window); fflush(stderr);
+
   init_window_icon();
   ren_init(window);