FIX: today's ipfilter "mutex not locked" panic

FWIW,

I've locally fixed the panics that some people mentioned today for
ipfilter with the following minor diff.  Now I can enable ipfilter
at boot time and still boot without panics.

--- patch begins ---
Index: sys/contrib/ipfilter/netinet/fil.c
===================================================================
RCS file: /home/ncvs/src/sys/contrib/ipfilter/netinet/fil.c,v
retrieving revision 1.38
diff -u -r1.38 fil.c
--- sys/contrib/ipfilter/netinet/fil.c	21 Jun 2004 22:46:35 -0000	1.38
+++ sys/contrib/ipfilter/netinet/fil.c	24 Jun 2004 19:17:33 -0000
_at__at_ -2155,9 +2155,6 _at__at_
 		ip_natsync(ifp);
 		ip_statesync(ifp);
 	}
-#  if defined(__FreeBSD_version) && (__FreeBSD_version >= 500043)
-	IFNET_RUNLOCK();
-#  endif
 	ip_natsync((struct ifnet *)-1);
 #  if defined(__FreeBSD_version) && (__FreeBSD_version >= 500043)
 	IFNET_RUNLOCK();
--- patch ends ---