lib, zebra: Add type and instance to nexthop update message

lib, zebra: Add type and instance to nexthop update message

Add the originating routes type and instance to the nexthop
update message.  This is necessary because there exist
scenarios where BGP needs to make a decision about the
originating route type and instance to know if it is
going to be doing a route replace to a route that would
resolve to itself.

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