Enable the -Wundef warning for clang

webrtc/modules/video_coding/timing_unittest.cc

 /*
  *  Copyright (c) 2011 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 <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 
 #include "webrtc/modules/video_coding/include/video_coding.h"
 #include "webrtc/modules/video_coding/internal_defines.h"
 #include "webrtc/modules/video_coding/timing.h"
 #include "webrtc/modules/video_coding/test/test_util.h"
 #include "webrtc/system_wrappers/include/clock.h"
 #include "webrtc/system_wrappers/include/trace.h"
 #include "webrtc/test/testsupport/fileutils.h"
 
 namespace webrtc {
@@ skipping 114 matching lines @@
     int64_t render_time =
         timing.RenderTimeMs(0xFFFFFFFFu, clock.TimeInMilliseconds());
     EXPECT_EQ(3 * 1000 / kFramerate, render_time);
     render_time = timing.RenderTimeMs(89u,  // One second later in 90 kHz.
                                       clock.TimeInMilliseconds());
     EXPECT_EQ(3 * 1000 / kFramerate + 1, render_time);
   }
 }
 
 }  // namespace webrtc