This allows SPT switchover for S,G upon receipt of packets
on the LHR.
1) When we create a *,G from a IGMP Group Report, install
the *,G route with the pimreg device on the OIL.
2) When a packet hits the LHR that matches the *,G, we will
get a WHOLEPKT callback from the kernel and if we cannot
find the S,G, that means we have matched it on the LHR via
the *,G mroute. Create the S,G start the KAT and run
inherited_olist.
3) When the S,G times out, safely remove the S,G via
the KAT expiry
4) When the *,G is removed, remove any S,G associated
with it via the LHR flag.
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>