GN win: prep_libc and fix tcmalloc linkage

base/allocator/prep_libc.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.
 #
 # This script takes libcmt.lib for VS2005/08/10/12/13 and removes the allocation
 # related functions from it.
 #
 # Usage: prep_libc.py <VCLibDir> <OutputDir> <arch>
 #
 # VCLibDir is the path where VC is installed, something like:
 #    C:\Program Files\Microsoft Visual Studio 8\VC\lib
 # OutputDir is the directory where the modified libcmt file should be stored.
-# arch is either 'ia32' or 'x64'
+# arch is one of: 'ia32', 'x86' or 'x64'. ia32 and x86 are synonyms.
 
 import os
 import shutil
 import subprocess
 import sys
 
 def run(command, filter=None):
   """Run |command|, removing any lines that match |filter|. The filter is
   to remove the echoing of input filename that 'lib' does."""
   popen = subprocess.Popen(
@@ skipping 35 matching lines @@
               'heapmin', 'sbheap', 'calloc', 'recalloc', 'calloc_impl',
               'new_mode', 'newopnt', 'newaopnt']
   for obj in objfiles:
     for vspath in vspaths:
       cmd = ('lib /nologo /ignore:4006,4014,4221 /remove:%s%s.obj %s' %
              (vspath, obj, output_lib))
       run(cmd, obj + '.obj')
 
 if __name__ == "__main__":
   sys.exit(main())