Fix xdiff lib build file for windows

xdiff/xinclude.h

 /*
  *  LibXDiff by Davide Libenzi ( File Differential Library )
  *  Copyright (C) 2003  Davide Libenzi
  *
  *  This library 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.
  *
  *  This library 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
  *  Lesser General Public License for more details.
  *
  *  You should have received a copy of the GNU Lesser General Public
  *  License along with this library; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
  *  Davide Libenzi <davidel@xmailserver.org>
  *
  */
 
 #if !defined(XINCLUDE_H)
 #define XINCLUDE_H
 
 #include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 #include <limits.h>
 
 #include "xmacros.h"
 #include "xdiff.h"
 #include "xtypes.h"
 #include "xutils.h"
 #include "xprepare.h"
 #include "xdiffi.h"
 #include "xemit.h"
 
 
 #endif /* #if !defined(XINCLUDE_H) */