zebra: Fix removal of routes on MetaQ when client goes down

zebra: Fix removal of routes on MetaQ when client goes down

It is possible that right before an upper level protocol dies
or is killed routes would be installed into zebra.  These routes
could be on the Meta-Q for early route-processing.  Leaving us with
a situation where the client is removed, and all it's routes that are
in the rib at that time, and then after that the MetaQ is run and the
routes are reprocessed leaving routes from an upper level daemon
post daemon going away from zebra's perspective.  These routes will
be abandoned.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>