Enable the -Wundef warning for clang

webrtc/modules/audio_processing/transient/moving_moments_unittest.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/modules/audio_processing/transient/moving_moments.h"
 
 #include <memory>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 
 namespace webrtc {
 
 static const float kTolerance = 0.0001f;
 
 class MovingMomentsTest : public ::testing::Test {
  protected:
   static const size_t kMovingMomentsBufferLength = 5;
   static const size_t kMaxOutputLength = 20;  // Valid for this tests only.
 
@@ skipping 172 matching lines @@
     moving_moments_->CalculateMoments(
         &kInput[i], 1, &output_mean_sample_based,
         &output_mean_squares_sample_based);
     EXPECT_FLOAT_EQ(output_mean_block_based[i], output_mean_sample_based);
     EXPECT_FLOAT_EQ(output_mean_squares_block_based[i],
                      output_mean_squares_sample_based);
   }
 }
 
 }  // namespace webrtc