bgpd, lib, ospf6d, ospfd, pimd, zebra: Rework routemap event callback

bgpd, lib, ospf6d, ospfd, pimd, zebra: Rework routemap event callback

The route_map_event_hook callback was passing the `route_map_event_t`
to each individual interested party.  No-one is ever using this data
so let's cut to the chase a bit and remove the pass through of data.
This is considered ok in that the routemap.c code came this way
originally and after 15+ years no-one is using this functionality.
Nor do I see any `easy` way to do anything useful with this data.

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