neg_find_zone
zone = neg_find_zone(neg, dname, dname_len, rrset_class);
zone = neg_find_zone(neg, signer, signer_len, dclass);
struct val_neg_zone* neg_find_zone(struct val_neg_cache* neg,
z = neg_find_zone(neg, (uint8_t*)zname, strlen(zname)+1,
zone = neg_find_zone(neg, dname, dname_len, rrset_class);
zone = neg_find_zone(neg, signer, signer_len, dclass);
struct val_neg_zone* neg_find_zone(struct val_neg_cache* neg,