Enable the -Wundef warning for clang

webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl_unittest.cc

 /*
  *  Copyright (c) 2016 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 <utility>
 #include <vector>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl.h"
 #include "webrtc/modules/audio_coding/audio_network_adaptor/mock/mock_controller.h"
 #include "webrtc/modules/audio_coding/audio_network_adaptor/mock/mock_controller_manager.h"
 #include "webrtc/modules/audio_coding/audio_network_adaptor/mock/mock_debug_dump_writer.h"
 
 namespace webrtc {
 
 using ::testing::_;
 using ::testing::NiceMock;
 using ::testing::Return;
@@ skipping 175 matching lines @@
 
   states.simulated_clock->AdvanceTimeMilliseconds(150);
   timestamp_check += 150;
   check.target_audio_bitrate_bps = rtc::Optional<int>(kTargetAudioBitrate);
   EXPECT_CALL(*states.mock_debug_dump_writer,
               DumpNetworkMetrics(NetworkMetricsIs(check), timestamp_check));
   states.audio_network_adaptor->SetTargetAudioBitrate(kTargetAudioBitrate);
 }
 
 }  // namespace webrtc