Apply patch to PhysicsWorld.gravity property.

Extras/LuaScript/pkgs/Physics/PhysicsWorld.pkg

@@ -108,3 +108,11 @@ public:
     tolua_property__get_set bool internalEdge;
     tolua_property__get_set bool splitImpulse;
 };
+
+${
+
+// Patch for PhysicsWorld.gravity property.
+#define TOLUA_DISABLE_tolua_get_PhysicsWorld_gravity
+#define tolua_get_PhysicsWorld_gravity tolua_PhysicsLuaAPI_PhysicsWorld_GetGravity00
+
+$}