Fix luabind::adl::object forward declare for clang

clang didn't like this, and GCC likes both :P

zone/lua_encounter.h

@@ -8,8 +8,10 @@ class Encounter;
 
 namespace luabind {
 	struct scope;
+	namespace adl {
 		class object;
 	}
+}
 
 luabind::scope lua_register_encounter();
 

zone/lua_mob.h

@@ -11,8 +11,10 @@ class Lua_ItemInst;
 
 namespace luabind {
 	struct scope;
+	namespace adl {
 		class object;
 	}
+}
 
 luabind::scope lua_register_mob();
 luabind::scope lua_register_special_abilities();