add PRESUBMIT for native_client_sdk.

native_client_sdk/src/build_tools/sdk_tools/set_nacl_env.py

 #!/usr/bin/env python
 # 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.
 
 ''' A tool to setup the NaCl build env and invoke a command such as make '''
 
 __author__ = 'gwink@google.com (Georges Winkenbach)'
 
 import optparse
 import os
-import re
 import subprocess
 import sys
 
 # The default sdk platform to use if the user doesn't specify one.
 __DEFAULT_SDK_PLATFORM = 'pepper_15'
 
 # Usage info.
 __GLOBAL_HELP = '''%prog options [command]
 
 set-nacl-env is a utility that sets up the environment required to build
@@ skipping 461 matching lines @@
   # Verify that we're running on a supported host.
   if sys.platform not in __PLATFORM_TO_HOST_MAP:
     sys.stderr.write('Platform %s is not supported.' % sys.platform)
     return 1
 
   return GenerateBuildSettings(options, args)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))