Enable the -Wundef warning for clang

webrtc/system_wrappers/source/data_log_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 "webrtc/system_wrappers/include/data_log.h"
 
 #include <map>
 #include <string>
 
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/system_wrappers/include/data_log_c.h"
 #include "webrtc/system_wrappers/source/data_log_c_helpers_unittest.h"
 
 using ::webrtc::DataLog;
 
 // A class for storing the values expected from a log table column when
 // verifying a log table file.
 struct ExpectedValues {
  public:
   ExpectedValues()
@@ skipping 275 matching lines @@
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestInsertArray_int32());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestNextRow());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestInsertCell_uint32());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestInsertArray_uint32());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestNextRow());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestInsertCell_int64());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestInsertArray_int64());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestNextRow());
   EXPECT_EQ(0, WebRtcDataLogCHelper_TestReturnLog());
 }