treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 407

Based on 1 normalized pattern(s):

  this application is free software you can redistribute it and or
  modify it under the terms of the gnu general public license as
  published by the free software foundation version 2 this application
  is distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 1 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190112.401137591@linutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/perf/python/twatch.py

 #! /usr/bin/python
+# SPDX-License-Identifier: GPL-2.0-only
 # -*- python -*-
 # -*- coding: utf-8 -*-
 #   twatch - Experimental use of the perf python interface
 #   Copyright (C) 2011 Arnaldo Carvalho de Melo <acme@redhat.com>
 #
-#   This application is free software; you can redistribute it and/or
-#   modify it under the terms of the GNU General Public License
-#   as published by the Free Software Foundation; version 2.
-#
-#   This application is distributed in the hope that it will be useful,
-#   but WITHOUT ANY WARRANTY; without even the implied warranty of
-#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-#   General Public License for more details.
 
 import perf