Revert "Extend the mDNS package with a native extension used on Mac OS"

src/pkg/mdns/mdns_extension.h

Index: src/pkg/mdns/mdns_extension.h
diff --git a/src/pkg/mdns/mdns_extension.h b/src/pkg/mdns/mdns_extension.h
deleted file mode 100644
index 04cf199e803b7f384edbc95ede0646ba7e10b2f3..0000000000000000000000000000000000000000
--- a/src/pkg/mdns/mdns_extension.h
+++ /dev/null
@@ -1,20 +0,0 @@
-// 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);
-
-#endif