NaCl/GYP: remove references to prep_toolchain.

third_party/libevent/libevent_nacl_nonsfi.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': [
     '../../build/common_untrusted.gypi',
   ],
   'conditions': [
     ['disable_nacl==0 and disable_nacl_untrusted==0', {
@@ skipping 22 matching lines @@
           ],
           'variables': {
             'nacl_untrusted_build': 1,
             'nlib_target': 'libevent_nacl_nonsfi.a',
             'build_glibc': 0,
             'build_newlib': 0,
             'build_irt': 0,
             'build_pnacl_newlib': 0,
             'build_nonsfi_helper': 1,
           },
-          'dependencies': [
-            '../../native_client/tools.gyp:prep_toolchain',
-          ],
         },
       ],
     }],
   ],
 }