progress: Use the same GPL boilerplate as most hg files

hgext/progress.py

@@ -2,19 +2,8 b''
 #
 # Copyright (C) 2010 Augie Fackler <[e-mail]>
 #
-# This program 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; either version 2 of the License, or (at your
-# option) any later version.
-#
-# This program 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.
-#
-# You should have received a copy of the GNU General Public License along
-# with this program; if not, write to the Free Software Foundation, Inc.,
-# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
 
 """show progress bars for some actions