Remove the preprocessor symbol WEBRTC_CODEC_PCM16 (it was always defined)

webrtc/modules/audio_coding/neteq/neteq.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 114 matching lines @@
             '<(DEPTH)/testing/gtest.gyp:gtest',
             '<(webrtc_root)/common_audio/common_audio.gyp:common_audio',
             '<(webrtc_root)/test/test.gyp:test_support_main',
           ],
           'defines': [
             'AUDIO_DECODER_UNITTEST',
             'WEBRTC_CODEC_G722',
             'WEBRTC_CODEC_ILBC',
             'WEBRTC_CODEC_ISACFX',
             'WEBRTC_CODEC_ISAC',
-            'WEBRTC_CODEC_PCM16',
             '<@(neteq_defines)',
           ],
           'sources': [
             'audio_decoder_impl.cc',
             'audio_decoder_impl.h',
             'audio_decoder_unittest.cc',
           ],
           'conditions': [
             ['OS=="android"', {
               'dependencies': [
@@ skipping 68 matching lines @@
               'sources': [
                 'audio_decoder_unittests.isolate',
               ],
             },
           ],
         }],
       ],
     }], # include_tests
   ], # conditions
 }