Update the mDNS native extension for Mac OS to handle PTR and SRV records

src/pkg/mdns/mdns_extension.h

 // Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE.md file.
 
 #ifndef MDNS_EXTENSION_H_
 #define MDNS_EXTENSION_H_
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 
 // Requests Ids. This should be aligned with the Dart code.
 enum RequestType {
   kEchoRequest = 0,
   kLookupRequest = 1
 };
 
 void HandleEcho(Dart_Port reply_port, Dart_CObject* argument);
-void HandleLookup(Dart_Port port_id, char* address);
+void HandleLookup(Dart_Port port_id, int type, char* fullname);
 
 #endif