Enable the -Wundef warning for clang

webrtc/modules/audio_coding/neteq/timestamp_scaler_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/timestamp_scaler.h"
 
-#include "testing/gmock/include/gmock/gmock.h"
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gmock.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.h"
 #include "webrtc/modules/audio_coding/neteq/mock/mock_decoder_database.h"
 #include "webrtc/modules/audio_coding/neteq/packet.h"
 
 using ::testing::Return;
 using ::testing::ReturnNull;
 using ::testing::_;
 
 namespace webrtc {
 
@@ skipping 279 matching lines @@
   uint32_t timestamp = 4711;  // Some number.
   EXPECT_EQ(timestamp, scaler.ToInternal(timestamp, kRtpPayloadType));
 
   Packet* packet = NULL;
   scaler.ToInternal(packet);  // Should not crash. That's all we can test.
 
   EXPECT_CALL(db, Die());  // Called when database object is deleted.
 }
 
 }  // namespace webrtc