dns_gethostbyname_addrtype() function

the hostname that is to be queried

pointer to a ip_addr_t where to store the address if it is already cached in the dns_table (only valid if ERR_OK is returned!)

a callback function to be called on success, failure or timeout (only if ERR_INPROGRESS is returned!)

argument to pass to the callback function

- LWIP_DNS_ADDRTYPE_IPV4_IPV6: try to resolve IPv4 first, try IPv6 if IPv4 fails only - LWIP_DNS_ADDRTYPE_IPV6_IPV4: try to resolve IPv6 first, try IPv4 if IPv6 fails only - LWIP_DNS_ADDRTYPE_IPV4: try to resolve IPv4 only - LWIP_DNS_ADDRTYPE_IPV6: try to resolve IPv6 only