Update GPL license headers, wrong address for FSF

- Update last paragraph, with FSF address
- Drop gratuitous "this file is part of the sysklogd package"
- Fix indentation
- Update copyright years for my own contributions

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/module.h

@@ -2,11 +2,10 @@
  * SPDX-License-Identifier: GPL-2.0-or-later
  *
  * module.h - Miscellaneous module definitions
+ *
  * Copyright (c) 1996 Richard Henderson <rth@tamu.edu>
  * Copyright (c) 2004-7 Martin Schulze <joey@infodrom.org>
  *
- * This file is part of the sysklogd package.
- *
  * 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
@@ -17,10 +16,9 @@
  * 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 file; see the file COPYING.  If not, write to the
- * Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,
- * MA 02110-1301, USA.
+ * 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.
  */
 
 #ifndef SYSKLOGD_MODULE_H_