Prefer default route when checking local interface addresses

First, let us assume that all network interfaces for IP host that runs Tor instance are internal as judged by tor_addr_is_internal() function.

There is the following code in get_interface_address6() function.

  /* Try to do this the smart way if possible. */
  if ((addrs = get_interface_addresses_raw(severity))) {
    int rv = -1;
    SMARTLIST_FOREACH_BEGIN(addrs, tor_addr_t *, a) {
      if (family != AF_UNSPEC && family != tor_addr_family(a))
        continue;
      if (tor_addr_is_loopback(a) ||
          tor_addr_is_multicast(a))
        continue;

      tor_addr_copy(addr, a);
      rv = 0;

      /* If we found a non-internal address, declare success.  Otherwise,
       * keep looking. */
      if (!tor_addr_is_internal(a, 0))
        break;
    } SMARTLIST_FOREACH_END(a);

    SMARTLIST_FOREACH(addrs, tor_addr_t *, a, tor_free(a));
    smartlist_free(addrs);
    return rv;
  }

Caller will get the last entry from a interface address smartlist. Is this okay?