Drop egress multicast on clat interface

Multicast packets on the clat interface are not supported,
so drop them in both clatd and its associated bpf offload.
This is required because NsdManager will start sending mDNS
packets on the clat interface as the check for
IFF_POINTOPOINT was removed.

Ingress multicast packets are already dropped elsewhere.

Test: TH
Change-Id: Icd22ca7f263ea5ff5244c17276ebb1002f72e842
2 files changed