zebra: remove recursively derived static routes correctly

zebra: remove recursively derived static routes correctly

Problem reported that in certain configs, when a router is initially
booted and the link is bounced, we can end up with a bogus static route
in the table.  This was due to the assumption in zebra_rnh that a static
route would not be recursively resolved through another static route with
a different next-hop. This fix changes this assumption.  Tested manually
and bgp-min, ospf-min, and vrf-min run with no new failures.

Ticket: CM-13328
Signed-off-by: Don Slice
Reviewed-by: CCR-5338