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

src/untrusted/crash_dump/decode_dump.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.
 
 """Utility to decode a crash dump generated by untrusted_crash_dump.[ch]
 
 Currently this produces a simple stack trace.
 """
 
 import json
@@ skipping 181 matching lines @@
       addr2line=options.add2line,
       library_paths=options.library_paths,
       platform=options.platform)
   info = decoder.LoadAndDecode(args[0])
   trace = decoder.StackTrace(info)
   decoder.PrintTrace(trace, sys.stdout)
 
 
 if __name__ == '__main__':
   Main(sys.argv[1:])