Enable the -Wundef warning for clang

webrtc/modules/audio_coding/neteq/normal_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.
  */
 
 // Unit tests for Normal class.
 
 #include "webrtc/modules/audio_coding/neteq/normal.h"
 
 #include <memory>
 #include <vector>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
 #include "webrtc/modules/audio_coding/neteq/audio_multi_vector.h"
 #include "webrtc/modules/audio_coding/neteq/background_noise.h"
 #include "webrtc/modules/audio_coding/neteq/expand.h"
 #include "webrtc/modules/audio_coding/neteq/mock/mock_decoder_database.h"
 #include "webrtc/modules/audio_coding/neteq/mock/mock_expand.h"
 #include "webrtc/modules/audio_coding/neteq/random_vector.h"
 #include "webrtc/modules/audio_coding/neteq/statistics_calculator.h"
 #include "webrtc/modules/audio_coding/neteq/sync_buffer.h"
 
@@ skipping 138 matching lines @@
 
   EXPECT_EQ(kPacketsizeBytes, output.Size());
 
   EXPECT_CALL(db, Die());      // Called when |db| goes out of scope.
   EXPECT_CALL(expand, Die());  // Called when |expand| goes out of scope.
 }
 
 // TODO(hlundin): Write more tests.
 
 }  // namespace webrtc