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

webrtc/modules/audio_processing/audio_processing.gypi

 # 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.
 
 {
   'variables': {
@@ skipping 113 matching lines @@
         'utility/block_mean_calculator.h',
         'utility/blocker.cc',
         'utility/blocker.h',
         'utility/delay_estimator.c',
         'utility/delay_estimator.h',
         'utility/delay_estimator_internal.h',
         'utility/delay_estimator_wrapper.c',
         'utility/delay_estimator_wrapper.h',
         'utility/lapped_transform.cc',
         'utility/lapped_transform.h',
-        'utility/ring_buffer.cc',
+        'utility/ring_buffer.c',
         'utility/ring_buffer.h',
         'vad/common.h',
         'vad/gmm.cc',
         'vad/gmm.h',
         'vad/noise_gmm_tables.h',
         'vad/pitch_based_vad.cc',
         'vad/pitch_based_vad.h',
         'vad/pitch_internal.cc',
         'vad/pitch_internal.h',
         'vad/pole_zero_filter.cc',
@@ skipping 133 matching lines @@
         'sources': [
           'aec/aec_core_neon.cc',
           'aec/aec_rdft_neon.c',
           'aecm/aecm_core_neon.c',
           'ns/nsx_core_neon.c',
         ],
       }],
     }],
   ],
 }