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

src/trusted/validator/driver/ncval_annotate.py

-#!/usr/bin/python
+#!/usr/bin/env python
 
 # Copyright (c) 2011 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 re
 import subprocess
 import sys
 
@@ skipping 106 matching lines @@
         PrintErrors(binary, errors)
         errors = []
       print line.rstrip()
 
   if errors:
     PrintErrors(binary, errors)
 
 
 if __name__ == '__main__':
   main()