maint: update copyrights for 2013 and as per current GNU standards

tests/atlocal.in

@@ -1,6 +1,21 @@
 # @configure_input@                                     -*- shell-script -*-
 # Configurable variable values for tar test suite.
-# Copyright (C) 2004, 2006 Free Software Foundation, Inc.
+# Copyright 2004, 2006, 2013 Free Software Foundation, Inc.
+
+# This file is part of GNU tar.
+
+# GNU tar 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 3 of the License, or
+# (at your option) any later version.
+
+# GNU tar 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, see <http://www.gnu.org/licenses/>.
 
 PATH=@abs_builddir@:@abs_top_builddir@/src:@abs_top_srcdir@/build-aux:$top_srcdir:$srcdir:$PATH