ACM: Remove functions related to DTMF

webrtc/modules/audio_coding/main/acm2/audio_coding_module.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.
  */
 
@@ skipping 87 matching lines @@
   } else {
     return true;
   }
 }
 
 AudioCoding::Config::Config()
     : neteq_config(),
       clock(Clock::GetRealTimeClock()),
       transport(nullptr),
       vad_callback(nullptr),
-      play_dtmf(true),
       initial_playout_delay_ms(0),
       playout_channels(1),
       playout_frequency_hz(32000) {
 }
 
 AudioCoding* AudioCoding::Create(const Config& config) {
   return new AudioCodingImpl(config);
 }
 
 }  // namespace webrtc