Pass Type to luax_register_type by pointer instead of reference

Since the type is passed to va_start, and apparently that's undefined behaviour if it's a reference.

<Textmode> the best kind of behavior

--HG--
branch : dynamiccore2

src/modules/graphics/opengl/wrap_Canvas.cpp

@@ -112,7 +112,7 @@ static const luaL_Reg w_Canvas_functions[] =
 
 extern "C" int luaopen_canvas(lua_State *L)
 {
-	return luax_register_type(L, Canvas::type, w_Texture_functions, w_Canvas_functions, nullptr);
+	return luax_register_type(L, &Canvas::type, w_Texture_functions, w_Canvas_functions, nullptr);
 }
 
 } // opengl