This allows for CARP interfaces to be used in jails e.g.
ip4.addr = "em0|10.10.1.20/32 vhid 1 pass MyPass advskew 100"
Before this change using exec.prestart to configure a CARP address
would result in the wrong MAC being broadcast on startup as jail creates
IP aliases to support ip[4|6].addr before exec.prestart is executed.
PR: 191832
Reviewed by: jamie
MFC after: 1 week
X-MFC-With: r269340
Phabric: D528
Sponsored by: Multiplay
b22b6abd34