maint: add license headers.

* examples/calc++/test, examples/variant.yy, AUTHORS, THANKS,
	* tests/atlocal.in, tests/bison.in: Add license headers.
	Reported by Tys Lefering.

examples/calc++/test

@@ -1,5 +1,20 @@
 #! /bin/sh
 
+# Copyright (C) 2005-2012 Free Software Foundation, Inc.
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+
 test -z "$VERBOSE" && {
    exec > /dev/null 2>&1
    set -x