ipmgmt_persist_if_exists
gif_exists = ipmgmt_persist_if_exists(uargp->ia_gifname,
if (!ipmgmt_persist_if_exists(uargp->ia_mifname, AF_UNSPEC)) {
extern boolean_t ipmgmt_persist_if_exists(const char *, sa_family_t);
!ipmgmt_persist_if_exists(pif->pif_ifname, AF_INET)) {
!ipmgmt_persist_if_exists(pif->pif_ifname, AF_INET6)) {