Enable the -Wundef warning for clang

webrtc/base/random_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 <math.h>
 
 #include <limits>
 #include <vector>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/base/mathutils.h"  // unsigned difference
 #include "webrtc/base/random.h"
 
 namespace webrtc {
 
 namespace {
 // Computes the positive remainder of x/n.
 template <typename T>
 T fdiv_remainder(T x, T n) {
   RTC_CHECK_GE(n, static_cast<T>(0));
@@ skipping 273 matching lines @@
     double f_mid = kScale * exp((n - kMean) * (n - kMean) / kDiv);
     double f_right = kScale * exp((n - kMean + 0.5) * (n - kMean + 0.5) / kDiv);
     double normal_dist = (f_left + 4 * f_mid + f_right) / 6;
     // Expect the number of samples to be within 3 standard deviations
     // (rounded up) of the expected number of samples in the bucket.
     EXPECT_NEAR(buckets[n], kN * normal_dist, 3 * sqrt(kN * normal_dist) + 1);
   }
 }
 
 }  // namespace webrtc