Enable the -Wundef warning for clang

webrtc/modules/audio_coding/neteq/mock/mock_audio_decoder.h

 /*
  *  Copyright (c) 2012 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.
  */
 
 #ifndef WEBRTC_MODULES_AUDIO_CODING_NETEQ_MOCK_MOCK_AUDIO_DECODER_H_
 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_MOCK_MOCK_AUDIO_DECODER_H_
 
 #include "webrtc/modules/audio_coding/codecs/audio_decoder.h"
 
-#include "testing/gmock/include/gmock/gmock.h"
+#include "webrtc/test/gmock.h"
 
 namespace webrtc {
 
 class MockAudioDecoder : public AudioDecoder {
  public:
   MockAudioDecoder() {}
   virtual ~MockAudioDecoder() { Die(); }
   MOCK_METHOD0(Die, void());
   MOCK_METHOD5(DecodeInternal,
                int(const uint8_t*, size_t, int, int16_t*, SpeechType*));
   MOCK_CONST_METHOD0(HasDecodePlc, bool());
   MOCK_METHOD2(DecodePlc, size_t(size_t, int16_t*));
   MOCK_METHOD0(Reset, void());
   MOCK_METHOD5(IncomingPacket, int(const uint8_t*, size_t, uint16_t, uint32_t,
                                    uint32_t));
   MOCK_METHOD0(ErrorCode, int());
   MOCK_CONST_METHOD2(PacketDuration, int(const uint8_t*, size_t));
   MOCK_CONST_METHOD0(Channels, size_t());
   MOCK_CONST_METHOD0(SampleRateHz, int());
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_MOCK_MOCK_AUDIO_DECODER_H_