Enable the -Wundef warning for clang

webrtc/modules/video_coding/codecs/test/videoprocessor_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 "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/video_coding/include/mock/mock_video_codec_interface.h"
 #include "webrtc/modules/video_coding/codecs/test/mock/mock_packet_manipulator.h"
 #include "webrtc/modules/video_coding/codecs/test/videoprocessor.h"
 #include "webrtc/modules/video_coding/include/video_coding.h"
 #include "webrtc/test/testsupport/mock/mock_frame_reader.h"
 #include "webrtc/test/testsupport/mock/mock_frame_writer.h"
 #include "webrtc/test/testsupport/packet_reader.h"
 #include "webrtc/test/testsupport/unittest_utils.h"
 #include "webrtc/typedefs.h"
 
@@ skipping 57 matching lines @@
   // be more than initialized...
   VideoProcessorImpl video_processor(
       &encoder_mock_, &decoder_mock_, &frame_reader_mock_, &frame_writer_mock_,
       &packet_manipulator_mock_, config_, &stats_);
   ASSERT_TRUE(video_processor.Init());
   video_processor.ProcessFrame(0);
 }
 
 }  // namespace test
 }  // namespace webrtc