As with ifnet_byindex_ref(), don't return IFF_DYING interfaces from ifunit_ref().  ifunit() continues to return them.
As with ifnet_byindex_ref(), don't return IFF_DYING interfaces from
ifunit_ref().  ifunit() continues to return them.

MFC after:	3 weeks

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