**/*.py: use /usr/bin/env to find python

src/trusted/validator_x86/testscripts/compare_validators.py

-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import collections
 import glob
 import optparse
 import re
 import subprocess
 import sys
@@ skipping 253 matching lines @@
   if options.update:
     if stats['unexplained disagreements'] > 0:
       print '@validators_disagree sections were created'
   else:
     if stats['unexplained disagreements'] > 0:
       sys.exit(1)
 
 
 if __name__ == '__main__':
   main(sys.argv[1:])