update diff-delta.c copyright

There is actually nothing left from the original LibXDiff code I used
over 2 years ago, and even the GIT implementation has diverged quite a
bit from LibXDiff's at this point.  Let's update the copyright notice
to better reflect that fact.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff-delta.c

@@ -1,21 +1,14 @@
 /*
  * diff-delta.c: generate a delta between two buffers
  *
- *  Many parts of this file have been lifted from LibXDiff version 0.10.
- *  http://www.xmailserver.org/xdiff-lib.html
+ * This code was greatly inspired by parts of LibXDiff from Davide Libenzi
+ * http://www.xmailserver.org/xdiff-lib.html
  *
- *  LibXDiff was written by Davide Libenzi <davidel@xmailserver.org>
- *  Copyright (C) 2003	Davide Libenzi
+ * Rewritten for GIT by Nicolas Pitre <nico@cam.org>, (C) 2005-2007
  *
- *  Many mods for GIT usage by Nicolas Pitre <nico@cam.org>, (C) 2005.
- *
- *  This file is free software; you can redistribute it and/or
- *  modify it under the terms of the GNU Lesser General Public
- *  License as published by the Free Software Foundation; either
- *  version 2.1 of the License, or (at your option) any later version.
- *
- *  Use of this within git automatically means that the LGPL
- *  licensing gets turned into GPLv2 within this project.
+ * This code is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
  */
 
 #include "git-compat-util.h"