Revert of Moved the ringbuffer to be built using C++

webrtc/modules/audio_processing/aec/echo_cancellation_internal.h

 /*
  *  Copyright (c) 2012 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_PROCESSING_AEC_ECHO_CANCELLATION_INTERNAL_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_AEC_ECHO_CANCELLATION_INTERNAL_H_
 
 #include "webrtc/modules/audio_processing/aec/aec_core.h"
+extern "C" {
 #include "webrtc/modules/audio_processing/utility/ring_buffer.h"
+}
 
 namespace webrtc {
 
 typedef struct {
   int delayCtr;
   int sampFreq;
   int splitSampFreq;
   int scSampFreq;
   float sampFactor;  // scSampRate / sampFreq
   short skewMode;
@@ skipping 34 matching lines @@
   RingBuffer* far_pre_buf;  // Time domain far-end pre-buffer.
 
   int farend_started;
 
   AecCore* aec;
 } Aec;
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC_ECHO_CANCELLATION_INTERNAL_H_