NaCl/GYP: remove references to prep_toolchain.

sandbox/sandbox_nacl_nonsfi.gyp

 # Copyright 2015 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/common_untrusted.gypi',
@@ skipping 21 matching lines @@
               'linux/services/namespace_sandbox.cc',
               'linux/services/proc_util.cc',
               'linux/services/syscall_wrappers.cc',
               'linux/services/thread_helpers.cc',
               'linux/suid/client/setuid_sandbox_client.cc',
               # TODO(hidehiko): Support seccomp-bpf sandbox.
             ],
           },
           'dependencies': [
             '../base/base_nacl.gyp:base_nacl_nonsfi',
-            '../native_client/tools.gyp:prep_toolchain',
           ],
         },
       ],
     }],
   ],
 }