get_addr() should return -1 in case of error

[aafbsd]

Subject says it all:
getaddrinfo() returns positive values in case of errors. These get returned
to the caller:

    res = getaddrinfo(host, portnum, &hints, &addr);
    if (res == 0) {
            int addrlen = addr->ai_addrlen;
            /* Grab first result */
            memcpy(out, addr->ai_addr, addr->ai_addrlen);
            freeaddrinfo(addr);
            return addrlen;
    }
    return res;

But the caller check for negative values, e.g.:

    res = get_addr("resolver1.opendns.com", 53, AF_INET, 0, &query.destination);
    if (res < 0) return 1;
    ...
    dns4addr_len = get_addr(listen_ip4, port, AF_INET, AI_PASSIVE, &dns4addr);
    if (dns4addr_len < 0) {
    ...
    int addr6_res = get_addr(listen_ip6, port, AF_INET6, AI_PASSIVE, &dns6addr);
    if (addr6_res < 0) {