Add 3DS resolution

common/libretro_core_options.h

@@ -40,6 +40,7 @@ struct retro_core_option_definition option_defs_us[] = {
          { "360x400",   NULL },
          { "360x480",   NULL },
          { "400x224",   NULL },
+	 { "400x240",   NULL },
          { "480x272",   NULL },
          { "512x224",   NULL },
          { "512x240",   NULL },
@@ -65,7 +66,11 @@ struct retro_core_option_definition option_defs_us[] = {
          { "1920x1200", NULL },
          { NULL, NULL },
       },
+#ifdef _3DS
+      "400x240",
+#else
       "320x200"
+#endif
    },
    {
       "tyrquake_framerate",