examples: add license headers

Prompted by Rici Lake.
https://stackoverflow.com/questions/62658368/#comment110853985_62661621
Discussed with Paul Eggert.

* doc/bison.texi, examples/c/bistromathic/parse.y,
* examples/c/lexcalc/parse.y, examples/c/lexcalc/scan.l,
* examples/c/pushcalc/calc.y, examples/c/reccalc/parse.y,
* examples/c/reccalc/scan.l, examples/d/calc.y,
* examples/java/calc/Calc.y, examples/java/simple/Calc.y:
Install the GPL3+ header.

1 files changed, 19 insertions, 0 deletions

diff --git a/examples/java/calc/Calc.y b/examples/java/calc/Calc.y
index e9f89572..1caa48b7 100644
--- a/examples/java/calc/Calc.y
+++ b/examples/java/calc/Calc.y
@@ -1,3 +1,22 @@
+/* Parser and scanner for calc in Java.   -*- Java -*-
+
+   Copyright (C) 2018-2020 Free Software Foundation, Inc.
+
+   This file is part of Bison, the GNU Compiler Compiler.
+
+   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/>.  */
+
 %language "Java"
 
 %define api.parser.class {Calc}