Fix python scripts in src/tools/

tools/code_coverage/croc_test.py

-#!/usr/bin/python2.4
+#!/usr/bin/env python
 #
 # Copyright 2009, Google Inc.
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #        * Redistributions of source code must retain the above copyright
 #    notice, this list of conditions and the following disclaimer.
@@ skipping 772 matching lines @@
   # TODO: test: less important, since these are thin wrappers around other
   # tested methods.
   #     ParseConfig()
   #     ParseLcovFile()
   #     PrintTree()
 
 #------------------------------------------------------------------------------
 
 if __name__ == '__main__':
   unittest.main()