Fix 743f2fcd5744744d649496d8f0524cf5ca7d3859.

The gethost is called from multicast testcases too, which I failed to
find, apologies everyone.

This commit moves the gethost to muticast directory and renames it to
mc_gethost and fixes all usages accordingly.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>