NaCl/GYP: remove references to prep_toolchain.

third_party/usrsctp/usrsctp_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': 'usrsctplib_nacl',
       'type': 'none',
       'variables': {
         'nlib_target': 'libusrsctplib_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',
         '<(DEPTH)/third_party/boringssl/boringssl_nacl.gyp:boringssl_nacl',
       ],
       'sources': [
         # Note: sources list duplicated in GN build.
         'usrsctplib/netinet/sctp.h',
         'usrsctplib/netinet/sctp_asconf.c',
         'usrsctplib/netinet/sctp_asconf.h',
         'usrsctplib/netinet/sctp_auth.c',
         'usrsctplib/netinet/sctp_auth.h',
@@ skipping 71 matching lines @@
         'include_dirs': [
           'usrsctplib/',
           'usrsctplib/netinet',
         ],
       },
       'pnacl_cflags!': [ '-Werror', '-Wall' ],
       'pnacl_cflags': [ '-w' ],
     },  # target usrsctp
   ],  # targets
 }