Enable the -Wundef warning for clang

webrtc/modules/audio_coding/neteq/audio_decoder_unittest.cc

 /*
  *  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.
  */
 
 #include "webrtc/modules/audio_coding/neteq/audio_decoder_impl.h"
 
 #include <assert.h>
 #include <stdlib.h>
 
 #include <memory>
 #include <string>
 #include <vector>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/modules/audio_coding/codecs/g711/audio_decoder_pcm.h"
 #include "webrtc/modules/audio_coding/codecs/g711/audio_encoder_pcm.h"
 #include "webrtc/modules/audio_coding/codecs/g722/audio_decoder_g722.h"
 #include "webrtc/modules/audio_coding/codecs/g722/audio_encoder_g722.h"
 #include "webrtc/modules/audio_coding/codecs/ilbc/audio_decoder_ilbc.h"
 #include "webrtc/modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.h"
 #include "webrtc/modules/audio_coding/codecs/isac/fix/include/audio_decoder_isacfix.h"
 #include "webrtc/modules/audio_coding/codecs/isac/fix/include/audio_encoder_isacfix.h"
 #include "webrtc/modules/audio_coding/codecs/isac/main/include/audio_decoder_isac.h"
 #include "webrtc/modules/audio_coding/codecs/isac/main/include/audio_encoder_isac.h"
@@ skipping 667 matching lines @@
   EXPECT_TRUE(CodecSupported(NetEqDecoder::kDecoderCNGnb));
   EXPECT_TRUE(CodecSupported(NetEqDecoder::kDecoderCNGwb));
   EXPECT_TRUE(CodecSupported(NetEqDecoder::kDecoderCNGswb32kHz));
   EXPECT_TRUE(CodecSupported(NetEqDecoder::kDecoderCNGswb48kHz));
   EXPECT_TRUE(CodecSupported(NetEqDecoder::kDecoderArbitrary));
   EXPECT_EQ(has_opus, CodecSupported(NetEqDecoder::kDecoderOpus));
   EXPECT_EQ(has_opus, CodecSupported(NetEqDecoder::kDecoderOpus_2ch));
 }
 
 }  // namespace webrtc