Enable the -Wundef warning for clang

webrtc/call/rtc_event_log_helper_thread.h

 /*
  *  Copyright (c) 2016 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.
  */
 
 #ifndef WEBRTC_CALL_RTC_EVENT_LOG_HELPER_THREAD_H_
 #define WEBRTC_CALL_RTC_EVENT_LOG_HELPER_THREAD_H_
 
 #include <limits>
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/event.h"
+#include "webrtc/base/ignore_wundef.h"
 #include "webrtc/base/platform_thread.h"
 #include "webrtc/base/swap_queue.h"
 #include "webrtc/call/ringbuffer.h"
 #include "webrtc/system_wrappers/include/clock.h"
 #include "webrtc/system_wrappers/include/file_wrapper.h"
 
 #ifdef ENABLE_RTC_EVENT_LOG
 // Files generated at build-time by the protobuf compiler.
+RTC_PUSH_IGNORING_WUNDEF()
 #ifdef WEBRTC_ANDROID_PLATFORM_BUILD
 #include "external/webrtc/webrtc/call/rtc_event_log.pb.h"
 #else
 #include "webrtc/call/rtc_event_log.pb.h"
 #endif
+RTC_POP_IGNORING_WUNDEF()
 #endif
 
 #ifdef ENABLE_RTC_EVENT_LOG
 
 namespace webrtc {
 
 class RtcEventLogHelperThread final {
  public:
   struct ControlMessage {
     ControlMessage()
@@ skipping 75 matching lines @@
   const Clock* const clock_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(RtcEventLogHelperThread);
 };
 
 }  // namespace webrtc
 
 #endif  // ENABLE_RTC_EVENT_LOG
 
 #endif  // WEBRTC_CALL_RTC_EVENT_LOG_HELPER_THREAD_H_