sdl: print the reason why SDL thinks SDL_Init failed before exiting

Signed-off-by: malc <av1474@comtv.ru>

sdl.c

@@ -849,7 +849,8 @@ void sdl_display_init(DisplayState *ds, int full_screen, int no_frame)
 
     flags = SDL_INIT_VIDEO | SDL_INIT_NOPARACHUTE;
     if (SDL_Init (flags)) {
-        fprintf(stderr, "Could not initialize SDL - exiting\n");
+        fprintf(stderr, "Could not initialize SDL(%s) - exiting\n",
+                SDL_GetError());
         exit(1);
     }
     vi = SDL_GetVideoInfo();