Probable typo for IPv6 size in MacOS

[gregjesl]

When compiling on MacOS Catalina:

mdns/mdns.h:646:27: error: use of undeclared identifier 'saddr6'
                addr6.sin6_len = sizeof(saddr6);

It looks like

mdns/mdns.h

Line 646 in 7e1050d

addr6.sin6_len = sizeof(saddr6);

should be

addr6.sin6_len = sizeof(addr6);