For some reason, MCAST_JOIN_GROUP is not working under uClinux. We can
just stick with the more traditional method.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Even though the MCAST_JOIN_GROUP socket option includes the interface
index, this applies to the received packets only. To bind the outgoing
packets to a particular interface, the IP_MULTICAST_IF option is needed.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>