Enable the -Wundef warning for clang

webrtc/modules/video_coding/frame_buffer2_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 "webrtc/modules/video_coding/frame_buffer2.h"
 
 #include <algorithm>
 #include <cstring>
 #include <limits>
 #include <vector>
 
-#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/base/platform_thread.h"
 #include "webrtc/base/random.h"
 #include "webrtc/modules/video_coding/frame_object.h"
 #include "webrtc/modules/video_coding/jitter_estimator.h"
 #include "webrtc/modules/video_coding/sequence_number_util.h"
 #include "webrtc/modules/video_coding/timing.h"
 #include "webrtc/system_wrappers/include/clock.h"
 
 namespace webrtc {
 namespace video_coding {
@@ skipping 368 matching lines @@
   EXPECT_EQ(pid, InsertFrame(pid + 1, 1, ts, true, pid));
   EXPECT_EQ(pid, InsertFrame(pid + 2, 0, ts, false, pid + 1));
   EXPECT_EQ(pid, InsertFrame(pid + 2, 1, ts, true, pid + 1));
   EXPECT_EQ(pid, InsertFrame(pid + 3, 0, ts, false, pid + 2));
   EXPECT_EQ(pid + 3, InsertFrame(pid + 1, 0, ts, false, pid));
   EXPECT_EQ(pid + 3, InsertFrame(pid + 3, 1, ts, true, pid + 2));
 }
 
 }  // namespace video_coding
 }  // namespace webrtc