Updates to make install_third_party build gtest and gmock on windows.

build_tools/install_third_party.py

 #!/usr/bin/python
 # Copyright (c) 2010 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that be
 # found in the LICENSE file.
 
 """Build and install all the third-party tools and libraries required to build
 the SDK code.  To add a script, add it to the array |THIRD_PARTY_SCRIPTS|.
 Before running the scripts, a couple of environment variables get set:
   PYTHONPATH - append this script's dir to the search path for module import.
   NACL_SDK_ROOT - forced to point to the root of this repo.
 """
 
 import os
 import subprocess
 import sys
 
 THIRD_PARTY_SCRIPTS = [
     os.path.join('install_gtest', 'install_gtest.py'),
     os.path.join('install_boost', 'install_boost.py'),
 ]
 
 
 def main(argv):
-  # TODO(strotheide): This needs to work on windows, too.  See bug
-  # http://code.google.com/p/nativeclient/issues/detail?id=1122
-  if sys.platform == 'win32':
-    print "NaCl SDK does not install third party packages on Windows."
-    sys.exit(0)
-
   script_dir = os.path.abspath(os.path.dirname(__file__))
   sep_char = ';' if sys.platform == 'win32' else ':'
   os.putenv('PYTHONPATH', '%s%s%s' %(os.getenv('PYTHONPATH'),
                                      sep_char,
                                      script_dir))
   # Force NACL_SDK_ROOT to point to the toolchain in this repo.
   (nacl_sdk_root, _) = os.path.split(script_dir)
   os.putenv('NACL_SDK_ROOT', nacl_sdk_root)
   for script in THIRD_PARTY_SCRIPTS:
     print "Running install script: %s" % os.path.join(script_dir, script)
     py_command = ['%s %s' % (sys.executable, os.path.join(script_dir, script))]
     p = subprocess.Popen(py_command + argv, shell=True)
     assert p.wait() == 0
 
 
 if __name__ == '__main__':
   main(sys.argv[1:])