NaCl/GYP: remove references to prep_toolchain.

third_party/boringssl/boringssl_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': 'boringssl_nacl',
       'type': 'none',
       'variables': {
         'nlib_target': 'libboringssl_nacl.a',
         'build_glibc': 0,
         'build_newlib': 0,
         'build_pnacl_newlib': 1,
       },
       'dependencies': [
-        '<(DEPTH)/native_client/tools.gyp:prep_toolchain',
         '<(DEPTH)/native_client_sdk/native_client_sdk_untrusted.gyp:nacl_io_untrusted',
       ],
       'includes': [
         # Include the auto-generated gypi file.
         'boringssl.gypi'
       ],
       'sources': [
         '<@(boringssl_lib_sources)',
       ],
       'defines': [
@@ skipping 11 matching lines @@
           'src/include',
         ],
       },
       'pnacl_compile_flags': [
         '-Wno-sometimes-uninitialized',
         '-Wno-unused-variable',
       ],
     },  # target boringssl_nacl
   ],
 }