MFC r199287:   Fix a functional regression in multicast.
MFC r199287:
  Fix a functional regression in multicast.

  Userland daemons need to see IGMP traffic regardless of the group;
  omit the imo filter check if the proto is IGMP. The kernel part
  of IGMP will have already filtered appropriately at this point.

Submitted by:   Franz Struwig
Reported by:    Ivor Prebeg, Franz Struwig

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase