cosmetics: restore Copyright for files coming from old zebra code

Important to give credits back to original author ! so Kunihiro, here we go.
I did some extensions and improvements, but to be honnest I just didnt
fully remind what and which part was modified...

lib/Makefile

@@ -26,7 +26,7 @@ CFLAGS	 = -g -O2 $(INCLUDES) -Werror -Wall -Wunused -Wstrict-prototypes
 DEFS	 = -D_GNU_SOURCE
 COMPILE	 = $(CC) $(CFLAGS) $(DEFS)
 
-OBJS = 	memory.o mpool.o utils.o timer.o vector.o rbtree.o daemon.o \
+OBJS = 	memory.o utils.o timer.o vector.o rbtree.o daemon.o \
 	scheduler.o md5.o list_head.o pidfile.o prefix.o rt_table.o \
 	signals.o process.o logger.o buffer.o command.o vty.o \
 	pkt_buffer.o json_reader.o json_writer.o

lib/buffer.c

@@ -1,22 +1,7 @@
-/* SPDX-License-Identifier: AGPL-3.0-or-later */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
- * Soft:        The main goal of gtp-guard is to provide robust and secure
- *              extensions to GTP protocol (GPRS Tunneling Procol). GTP is
- *              widely used for data-plane in mobile core-network. gtp-guard
- *              implements a set of 3 main frameworks:
- *              A Proxy feature for data-plane tweaking, a Routing facility
- *              to inter-connect and a Firewall feature for filtering,
- *              rewriting and redirecting.
- *
- * Authors:     Alexandre Cassen, <[email protected]>
- *
- *              This program is free software; you can redistribute it and/or
- *              modify it under the terms of the GNU Affero General Public
- *              License Version 3.0 as published by the Free Software Foundation;
- *              either version 3.0 of the License, or (at your option) any later
- *              version.
- *
- * Copyright (C) 2023-2024 Alexandre Cassen, <[email protected]>
+ * Buffering of output and input.
+ * Copyright (C) 1998 Kunihiro Ishiguro
  */
 
 #include <stddef.h>

lib/buffer.h

@@ -1,22 +1,7 @@
-/* SPDX-License-Identifier: AGPL-3.0-or-later */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
- * Soft:        The main goal of gtp-guard is to provide robust and secure
- *              extensions to GTP protocol (GPRS Tunneling Procol). GTP is
- *              widely used for data-plane in mobile core-network. gtp-guard
- *              implements a set of 3 main frameworks:
- *              A Proxy feature for data-plane tweaking, a Routing facility
- *              to inter-connect and a Firewall feature for filtering,
- *              rewriting and redirecting.
- *
- * Authors:     Alexandre Cassen, <[email protected]>
- *
- *              This program is free software; you can redistribute it and/or
- *              modify it under the terms of the GNU Affero General Public
- *              License Version 3.0 as published by the Free Software Foundation;
- *              either version 3.0 of the License, or (at your option) any later
- *              version.
- *
- * Copyright (C) 2023-2024 Alexandre Cassen, <[email protected]>
+ * Buffering of output and input.
+ * Copyright (C) 1998 Kunihiro Ishiguro
  */
 
 #ifndef _BUFFER_H

lib/command.c

@@ -1,22 +1,7 @@
-/* SPDX-License-Identifier: AGPL-3.0-or-later */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
- * Soft:        The main goal of gtp-guard is to provide robust and secure
- *              extensions to GTP protocol (GPRS Tunneling Procol). GTP is
- *              widely used for data-plane in mobile core-network. gtp-guard
- *              implements a set of 3 main frameworks:
- *              A Proxy feature for data-plane tweaking, a Routing facility
- *              to inter-connect and a Firewall feature for filtering,
- *              rewriting and redirecting.
- *
- * Authors:     Alexandre Cassen, <[email protected]>
- *
- *              This program is free software; you can redistribute it and/or
- *              modify it under the terms of the GNU Affero General Public
- *              License Version 3.0 as published by the Free Software Foundation;
- *              either version 3.0 of the License, or (at your option) any later
- *              version.
- *
- * Copyright (C) 2023-2024 Alexandre Cassen, <[email protected]>
+ * Zebra configuration command interface routine
+ * Copyright (C) 1997, 98 Kunihiro Ishiguro
  */
 
 #include <ctype.h>

lib/command.h

@@ -1,22 +1,7 @@
-/* SPDX-License-Identifier: AGPL-3.0-or-later */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
- * Soft:        The main goal of gtp-guard is to provide robust and secure
- *              extensions to GTP protocol (GPRS Tunneling Procol). GTP is
- *              widely used for data-plane in mobile core-network. gtp-guard
- *              implements a set of 3 main frameworks:
- *              A Proxy feature for data-plane tweaking, a Routing facility
- *              to inter-connect and a Firewall feature for filtering,
- *              rewriting and redirecting.
- *
- * Authors:     Alexandre Cassen, <[email protected]>
- *
- *              This program is free software; you can redistribute it and/or
- *              modify it under the terms of the GNU Affero General Public
- *              License Version 3.0 as published by the Free Software Foundation;
- *              either version 3.0 of the License, or (at your option) any later
- *              version.
- *
- * Copyright (C) 2023-2024 Alexandre Cassen, <[email protected]>
+ * Zebra configuration command interface routine
+ * Copyright (C) 1997, 98 Kunihiro Ishiguro
  */
 
 #ifndef _COMMAND_H

lib/list_head.h

@@ -19,6 +19,8 @@
  * Copyright (C) 2023-2024 Alexandre Cassen, <[email protected]>
  */
 
+/* This file is copied from the Linux kernel include/linux/list.h file */
+
 #ifndef _LIST_HEAD_H
 #define _LIST_HEAD_H