bgpd, zebra: Use next hop tracking for connected routes too

Allow next hop tracking to work with connected routes
And cleanup obsolete code in bgp_scan and bgp_import.

Signed-off-by: Dinesh Dutt <ddutt@cumulusnetworks.com>
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
Edits: Paul Jakma <paul.jakma@hpe.com> Rebase re-ordering conflicts with
       NHT route-map, potential errors.
diff --git a/bgpd/bgp_packet.h b/bgpd/bgp_packet.h
index 6b0b7f4..74c62c0 100644
--- a/bgpd/bgp_packet.h
+++ b/bgpd/bgp_packet.h
@@ -40,6 +40,7 @@
 /* Packet send and receive function prototypes. */
 extern int bgp_read (struct thread *);
 extern int bgp_write (struct thread *);
+extern int bgp_connect_check (struct peer *, int change_state);
 
 extern void bgp_keepalive_send (struct peer *);
 extern void bgp_open_send (struct peer *);