Corrected include of C++ header file in AECM that was done using external inclusion

webrtc/modules/audio_processing/aecm/aecm_core.cc

 /*
  *  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.
  */
 
 #include "webrtc/modules/audio_processing/aecm/aecm_core.h"
 
 #include <assert.h>
 #include <stddef.h>
 #include <stdlib.h>
 
 extern "C" {
 #include "webrtc/common_audio/ring_buffer.h"
 #include "webrtc/common_audio/signal_processing/include/real_fft.h"
+}
 #include "webrtc/modules/audio_processing/aecm/echo_control_mobile.h"
+extern "C" {
 #include "webrtc/modules/audio_processing/utility/delay_estimator_wrapper.h"
 #include "webrtc/system_wrappers/include/cpu_features_wrapper.h"
 }
 #include "webrtc/typedefs.h"
 
 #ifdef AEC_DEBUG
 FILE *dfile;
 FILE *testfile;
 #endif
 
@@ skipping 1194 matching lines @@
         memcpy(farend + readPos, aecm->farBuf + aecm->farBufReadPos,
                sizeof(int16_t) * readLen);
         aecm->farBufReadPos = 0;
         readPos = readLen;
         readLen = farLen - readLen;
     }
     memcpy(farend + readPos, aecm->farBuf + aecm->farBufReadPos,
            sizeof(int16_t) * readLen);
     aecm->farBufReadPos += readLen;
 }