NaCl/GYP: remove references to prep_toolchain.

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,
       },
-      'dependencies': [
-        '<(DEPTH)/native_client/tools.gyp:prep_toolchain',
-      ],
       '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'
   ],
 }