mdns crash on multiple IPv6 link-local

[adienakhmad]

Hi, while playing around with the DNS-SD demo on my mac, the demo immediately crashes.

On a default mac os install, there are multiple interfaces with IPv6 link-local addresses. The addresses have scope in them, here's an example:

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        <snip>
        inet6 fe80::1cab:f562:602a:711e%en0 prefixlen 64 secured scopeid 0xb
        <snip>

With this setup, the library immediately crash with SocketException: no route to host.

[adienakhmad]

I've submitted PR #4 to fix this.