Enable the -Wundef warning for clang

webrtc/test/configurable_frame_size_encoder.cc

 /*
  *  Copyright (c) 2013 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/test/configurable_frame_size_encoder.h"
 
 #include <string.h>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 
 #include "webrtc/common_video/include/video_image.h"
 #include "webrtc/modules/video_coding/include/video_codec_interface.h"
 
 namespace webrtc {
 namespace test {
 
 ConfigurableFrameSizeEncoder::ConfigurableFrameSizeEncoder(
     size_t max_frame_size)
     : callback_(NULL),
@@ skipping 57 matching lines @@
 }
 
 int32_t ConfigurableFrameSizeEncoder::SetFrameSize(size_t size) {
   assert(size <= max_frame_size_);
   current_frame_size_ = size;
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
 }  // namespace test
 }  // namespace webrtc