Enable the -Wundef warning for clang

webrtc/modules/audio_coding/neteq/packet_buffer_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 PacketBuffer class.
 
 #include "webrtc/modules/audio_coding/neteq/packet_buffer.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"
 #include "webrtc/modules/audio_coding/neteq/tick_timer.h"
 
 using ::testing::Return;
 using ::testing::_;
 
 namespace webrtc {
 
@@ skipping 658 matching lines @@
 // Test the IsObsoleteTimestamp method with different limit timestamps.
 TEST(PacketBuffer, IsObsoleteTimestamp) {
   TestIsObsoleteTimestamp(0);
   TestIsObsoleteTimestamp(1);
   TestIsObsoleteTimestamp(0xFFFFFFFF);  // -1 in uint32_t.
   TestIsObsoleteTimestamp(0x80000000);  // 2^31.
   TestIsObsoleteTimestamp(0x80000001);  // 2^31 + 1.
   TestIsObsoleteTimestamp(0x7FFFFFFF);  // 2^31 - 1.
 }
 }  // namespace webrtc