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/zebra/zebra_rnh.h b/zebra/zebra_rnh.h
index 97dbba7..574c95f 100644
--- a/zebra/zebra_rnh.h
+++ b/zebra/zebra_rnh.h
@@ -30,6 +30,7 @@
 struct rnh
 {
   u_char flags;
+#define ZEBRA_NHT_CONNECTED  	0x1
   struct rib *state;
   struct list *client_list;
   struct route_node *node;