DNS_LOCAL_HOSTLIST macro

DNS_LOCAL_HOSTLIST: Implements a local host-to-address list. If enabled, you have to define an initializer: \#define DNS_LOCAL_HOSTLIST_INIT {DNS_LOCAL_HOSTLIST_ELEM("host_ip4", IPADDR4_INIT_BYTES(1,2,3,4)), \ DNS_LOCAL_HOSTLIST_ELEM("host_ip6", IPADDR6_INIT_HOST(123, 234, 345, 456)} Instead, you can also use an external function: \#define DNS_LOOKUP_LOCAL_EXTERN(x) extern err_t my_lookup_function(const char *name, ip_addr_t *addr, u8_t dns_addrtype) that looks up the IP address and returns ERR_OK if found (LWIP_DNS_ADDRTYPE_xxx is passed in dns_addrtype).