zebra: Set link-detect on by default

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Reviewed-by: Dinesh G Dutt <ddutt at cumulusnetworks.com>
Reviewed-by: Scott Feldman <sfeldma at cumulusnetworks.com>
diff --git a/lib/if.c b/lib/if.c
index 3a1f9b4..2b46a1b 100644
--- a/lib/if.c
+++ b/lib/if.c
@@ -132,6 +132,9 @@
   ifp->connected = list_new ();
   ifp->connected->del = (void (*) (void *)) connected_free;
 
+  /* Enable Link-detection by default */
+  SET_FLAG(ifp->status, ZEBRA_INTERFACE_LINKDETECTION);
+
   if (if_master.if_new_hook)
     (*if_master.if_new_hook) (ifp);