Fix python scripts in src/tools/

tools/site_compare/site_compare.py

-#!/usr/bin/python2.4
-# Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+#!/usr/bin/env python
+# Copyright (c) 2011 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.
 
 """SiteCompare component to handle bulk scrapes.
 
 Invokes a list of browsers and sends them to a list of URLs,
 saving the rendered results to a specified directory, then
 performs comparison operations on the resulting bitmaps and
 saves the results
 """
@@ skipping 149 matching lines @@
   """Main executable. Parse the command line and invoke the command."""
   cmdline = command_line.CommandLine()
 
   # The below two commands are currently unstable so have been disabled
   # commands.compare2.CreateCommand(cmdline)
   # commands.maskmaker.CreateCommand(cmdline)
   commands.measure.CreateCommand(cmdline)
   commands.scrape.CreateCommand(cmdline)
 
   cmdline.ParseCommandLine()
-
+  return 0
 
 
 if __name__ == "__main__":
-  main()
-
+  sys.exit(main())