Share the zygote's fopen overrides with nacl_helper.

chrome/nacl.gypi

 # Copyright (c) 2012 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.
 
 {
   'include': [
     '../native_client/build/untrusted.gypi',
   ],
   'target_defaults': {
     'variables': {
@@ skipping 123 matching lines @@
         ['OS=="linux"', {
           'targets': [
             {
               'target_name': 'nacl_helper',
               'type': 'executable',
               'include_dirs': [
                 '..',
               ],
               'dependencies': [
                 '../crypto/crypto.gyp:crypto',
+                '../sandbox/sandbox.gyp:libc_urandom_override',
                 'nacl',
               ],
               'sources': [
                 'nacl/nacl_helper_linux.cc',
                 '../base/posix/unix_domain_socket.cc',
                 '../chrome/common/nacl_messages.cc',
                 '../chrome/common/nacl_types.cc',
                 '../content/common/child_process_sandbox_support_impl_shm_linux.cc',
               ],
               'conditions': [
@@ skipping 40 matching lines @@
               'target_name': 'nacl_win64',
               'type': 'none',
               'sources': [],
             },
           ],
         }],
       ],
     }],
   ],
 }