domain_find_rrset_and_prev
collect_rrs->rrset = domain_find_rrset_and_prev(collect_rrs->domain, zone, collect_rrs->type, &collect_rrs->rrset_prev);
rrset = domain_find_rrset_and_prev(domain, zone, type, &rrset_prev);
rrset_type* domain_find_rrset_and_prev(domain_type* domain, zone_type* zone,
state->c.rrset = domain_find_rrset_and_prev(state->c.domain, state->zone, state->c.type, &state->c.rrset_prev);