Declare character encoding of python script

tools/starpu_trace_state_stats.py

@@ -1,9 +1,10 @@
 #!/usr/bin/python
+# -*- coding: utf-8 -*-
 # StarPU --- Runtime system for heterogeneous multicore architectures.
 #
 # Copyright (C) 2017                                     CNRS
 # Copyright (C) 2016                                     Inria
-# Copyright (C) 2016,2017                                Université de Bordeaux
+# Copyright (C) 2016,2017-2018                           Université de Bordeaux
 #
 # StarPU is free software; you can redistribute it and/or modify
 # it under the terms of the GNU Lesser General Public License as published by