MFC r363284-r363285, r363452, r363670

r363284:
pfil_run_hooks() can be called recursively, so we have to
define FASTROUTE_RECURSION in fil.c

Submitted by: christos@NetBSD.org
Reported by: christos@NetBSD.org
Obtained from: NetBSD r1.31

r363285:
Fix incorrect byte order in ipfstat -f output.

• make sure frag is initialized to 0
• initialize ipfr_p field

NetBSD PR: 55137
Submitted by: christos@NetBSD.org
Reported by: christos@NetBSD.org
Obtained from: NetBSD fil.c r1.32, ip_frag.c r1.8

r363452:
Load ipfilter, ipnat, and ippool rules, and start ipmon in a vnet jail.

PR: 248109
Reported by: joeb1@a1poweruser.com

r363670:
Continued ipfilter #ifdef cleanup. The r343701 log entry contains a
complete description.