Add a gyp/gn variable for whether to use iLBC or not

webrtc/modules/audio_coding/audio_coding.gypi

 # Copyright (c) 2015 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.
 
 {
   'includes': [
@@ skipping 14 matching lines @@
     'audio_coding_dependencies': [
       'cng',
       'g711',
       'pcm16b',
       '<(webrtc_root)/common.gyp:webrtc_common',
       '<(webrtc_root)/common_audio/common_audio.gyp:common_audio',
       '<(webrtc_root)/system_wrappers/system_wrappers.gyp:system_wrappers',
     ],
     'audio_coding_defines': [],
     'conditions': [
+      ['include_ilbc==1', {
+        'audio_coding_dependencies': ['ilbc',],
+        'audio_coding_defines': ['WEBRTC_CODEC_ILBC',],
+      }],
       ['include_opus==1', {
         'audio_coding_dependencies': ['webrtc_opus',],
         'audio_coding_defines': ['WEBRTC_CODEC_OPUS',],
       }],
       ['build_with_mozilla==0', {
         'conditions': [
           ['target_arch=="arm"', {
             'audio_coding_dependencies': ['isac_fix',],
             'audio_coding_defines': ['WEBRTC_CODEC_ISACFX',],
           }, {
             'audio_coding_dependencies': ['isac',],
             'audio_coding_defines': ['WEBRTC_CODEC_ISAC',],
           }],
         ],
         'audio_coding_dependencies': ['g722',],
         'audio_coding_defines': ['WEBRTC_CODEC_G722',],
       }],
       ['build_with_mozilla==0 and build_with_chromium==0', {
-        'audio_coding_dependencies': ['ilbc', 'red',],
-        'audio_coding_defines': ['WEBRTC_CODEC_ILBC', 'WEBRTC_CODEC_RED',],
+        'audio_coding_dependencies': ['red',],
+        'audio_coding_defines': ['WEBRTC_CODEC_RED',],
       }],
     ],
   },
   'targets': [
     {
       'target_name': 'rent_a_codec',
       'type': 'static_library',
       'defines': [
         '<@(audio_coding_defines)',
       ],
@@ skipping 139 matching lines @@
           'sources': [
              'test/insert_packet_with_timing.cc',
              'test/Channel.cc',
              'test/PCMFile.cc',
            ],
         }, # delay_test
       ],
     }],
   ],
 }