Fix SIGSEGV crash in networking code (bug was introduced in r6288).
Thanks to Gleb Natapov for finding this fix.

Signed-off-by: Stefan Weil <weil@mail.berlios.de>

Index: trunk/slirp/ip_input.c
===================================================================
--- trunk.orig/slirp/ip_input.c	2009-02-05 22:16:34.000000000 +0100
+++ trunk/slirp/ip_input.c	2009-02-05 22:17:02.000000000 +0100
@@ -392,8 +392,7 @@
 	 * into the new buffer.
 	 */
 	if (m->m_flags & M_EXT) {
-	  int delta;
-	  delta = (char *)ip - m->m_dat;
+	  int delta = (char *)q - m->m_dat;
 	  q = (struct ipasfrag *)(m->m_ext + delta);
 	}