Inline GPU and opus GYP files into GN build.

third_party/opus/opus_nacl.gyp

-# Copyright 2014 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-{
-  'includes': [
-    '../../native_client/build/untrusted.gypi',
-  ],
-  'targets': [
-    {
-      'target_name': 'opus_nacl',
-      'type': 'none',
-      'variables': {
-        'nlib_target': 'libopus_nacl.a',
-        'build_glibc': 0,
-        'build_newlib': 0,
-        'build_pnacl_newlib': 1,
-      },
-      'defines': [
-        'OPUS_BUILD',
-        'OPUS_EXPORT=',
-        'HAVE_LRINT',
-        'HAVE_LRINTF',
-        'VAR_ARRAYS',
-      ],
-      'include_dirs': [
-        'src/celt',
-        'src/include',
-        'src/silk',
-        'src/silk/float',
-      ],
-      'includes': ['opus_srcs.gypi', ],
-      'sources': [
-        '<@(opus_common_sources)',
-        '<@(opus_float_sources)',
-      ],
-      # Suppress a warning given by opus_decoder.c that tells us
-      # optimizations are turned off.
-      'cflags': [
-        '-Wno-#pragma-messages',
-      ],
-    },  # end of target 'opus_nacl'
-  ],
-}