call [Address_xorcmp][] over 4 hunks of the ipv6 address
in the address struct the data is stored like this:
uint32_t three_be;
uint32_t four_be;
uint32_t one_be;
uint32_t two_be;
compareNodes accesses them in counting order
ret = Address_xorcmp(0, na->address.ip6.ints.one_be, nb->address.ip6.ints.one_be);
if (ret) { return ret; }
ret = Address_xorcmp(0, na->address.ip6.ints.two_be, nb->address.ip6.ints.two_be);
if (ret) { return ret; }
ret = Address_xorcmp(0, na->address.ip6.ints.three_be, nb->address.ip6.ints.three_be);
if (ret) { return ret; }
ret = Address_xorcmp(0, na->address.ip6.ints.four_be, nb->address.ip6.ints.four_be);
if all of these values from node a are equal to node b return 0 if something other than 0 from Address_xorcmp return that.