Multicast socket options are shared between IPv4 and IPv6.
* xlat/sockipv6options.in: Add MCAST_JOIN_GROUP, MCAST_BLOCK_SOURCE,
MCAST_UNBLOCK_SOURCE, MCAST_LEAVE_GROUP, MCAST_JOIN_SOURCE_GROUP,
MCAST_LEAVE_SOURCE_GROUP, and MCAST_MSFILTER.
IPV6_IPSEC_POLICY
IPV6_XFRM_POLICY
IPV6_HDRINCL
+MCAST_JOIN_GROUP
+MCAST_BLOCK_SOURCE
+MCAST_UNBLOCK_SOURCE
+MCAST_LEAVE_GROUP
+MCAST_JOIN_SOURCE_GROUP
+MCAST_LEAVE_SOURCE_GROUP
+MCAST_MSFILTER
IPV6_RECVPKTINFO
IPV6_PKTINFO
IPV6_RECVHOPLIMIT