N3DS port (squashed)

A dedicated renderer using Citro3D would likely allow for better
much better graphical performances.

include/SDL_main.h

@@ -108,6 +108,15 @@
    void reset_IOP(); \
    void reset_IOP() {}
 
+#elif defined(__3DS__)
+/*
+  On N3DS, SDL provides a main function that sets up the screens
+  and storage.
+
+  If you provide this yourself, you may define SDL_MAIN_HANDLED
+*/
+#define SDL_MAIN_AVAILABLE
+
 #endif
 #endif /* SDL_MAIN_HANDLED */