[gjs: 8/18] maint: Add GPL license and copyright to example copied from Seed

[Philip Chimento <pchimento src gnome org>]

commit d908d992425dcb3561cfd9b1c80f2dfe6c4086e4
Author: Philip Chimento <philip chimento gmail com>
Date:   Sun Sep 13 10:56:00 2020 -0700

    maint: Add GPL license and copyright to example copied from Seed
    
    This example was originally copied from Seed's examples, so it gets the
    copyright and license information from Seed.

 examples/calc.js | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/examples/calc.js b/examples/calc.js
index 87e21b62..88b4358b 100644
--- a/examples/calc.js
+++ b/examples/calc.js
@@ -1,4 +1,6 @@
 #!/usr/bin/env gjs
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightText: 2008 Robert Carr <carrr rpi edu>
 
 imports.gi.versions.Gtk = '3.0';
 const {Gtk} = imports.gi;