Enable the -Wundef warning for clang

webrtc/modules/audio_coding/neteq/audio_classifier.h

 /*
  *  Copyright (c) 2014 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_MODULES_AUDIO_CODING_NETEQ_AUDIO_CLASSIFIER_H_
 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_AUDIO_CLASSIFIER_H_
 
+#include "webrtc/base/ignore_wundef.h"
+
 extern "C" {
+RTC_PUSH_IGNORING_WUNDEF()
 #include "celt.h"
+RTC_POP_IGNORING_WUNDEF()
 #include "analysis.h"
 #include "opus_private.h"
 }
 
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
 // This class provides a speech/music classification and is a wrapper over the
 // Opus classifier. It currently only supports 48 kHz mono or stereo with a
@@ skipping 19 matching lines @@
   AnalysisInfo analysis_info_;
   bool is_music_;
   float music_probability_;
   const CELTMode* celt_mode_;
   TonalityAnalysisState analysis_state_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_AUDIO_CLASSIFIER_H_