Fix python scripts in src/tools/

tools/gen_keyboard_overlay_data/gen_keyboard_overlay_data.py

-#!/usr/bin/python
+#!/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.
 
 """Generate keyboard layout and hotkey data for the keyboard overlay.
 
 This script fetches data from the keyboard layout and hotkey data spreadsheet,
 and output the data depending on the option.
 
   --cc: Rewrites a part of C++ code in
@@ skipping 545 matching lines @@
   if options.grd:
     OutputGrd(hotkey_data, options.outdir)
   if options.cc:
     OutputCC(hotkey_data, options.outdir)
   if options.altgr:
     OutputAltGr(keyboard_glyph_data, options.outdir)
 
 
 if __name__ == '__main__':
   main()