Allow more services to run in vnet jails

After some tests, here are the services that run into a vnet jail:

• defaultroute
• dhclient
• ip6addrctl
• natd
• pf
• pfsync
• pflog (deamon runs, pflog0 interface usable, but /var/log/pflog not filled)
• rarpd
• route6d (do nothing anyway because obsolete)
• routed (do nothing anyway because obsolete)
• rtsold
• static_arp
• static_ndp

PR: 220530
Submitted by: olivier@freebsd.org