Enable the -Wundef warning for clang

webrtc/voice_engine/test/channel_transport/channel_transport.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/voice_engine/test/channel_transport/channel_transport.h"
 
 #include <stdio.h>
 
 #if !defined(WEBRTC_ANDROID) && !defined(WEBRTC_IOS)
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 #endif
 #include "webrtc/voice_engine/test/channel_transport/udp_transport.h"
 #include "webrtc/voice_engine/include/voe_network.h"
 
 #if defined(WEBRTC_ANDROID) || defined(WEBRTC_IOS)
 #undef NDEBUG
 #include <assert.h>
 #endif
 
 namespace webrtc {
@@ skipping 47 matching lines @@
   return return_value;
 }
 
 int VoiceChannelTransport::SetSendDestination(const char* ip_address,
                                               uint16_t rtp_port) {
   return socket_transport_->InitializeSendSockets(ip_address, rtp_port);
 }
 
 }  // namespace test
 }  // namespace webrtc