Enable the -Wundef warning for clang

webrtc/modules/remote_bitrate_estimator/test/metric_recorder_unittest.cc

 /*
  *  Copyright (c) 2015 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/remote_bitrate_estimator/test/metric_recorder.h"
 
 #include <math.h>
 #include <algorithm>
 #include <vector>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 
 namespace webrtc {
 namespace testing {
 namespace bwe {
 
 class MetricRecorderTest : public ::testing::Test {
  public:
   MetricRecorderTest() : metric_recorder_("Test", 0, nullptr, nullptr) {}
 
   ~MetricRecorderTest() {}
@@ skipping 71 matching lines @@
 
   EXPECT_EQ(metric_recorder_.NthDelayPercentile(0), 1);
   EXPECT_EQ(metric_recorder_.NthDelayPercentile(5), (5 * kNumPackets) / 100);
   EXPECT_EQ(metric_recorder_.NthDelayPercentile(95), (95 * kNumPackets) / 100);
   EXPECT_EQ(metric_recorder_.NthDelayPercentile(100), kNumPackets);
 }
 
 }  // namespace bwe
 }  // namespace testing
 }  // namespace webrtc