zebra: Add link parameters support to Zebra

* zebra/interface.c:
   - Add new link-params CLI commands
   - Add new functions to set/get link parameters for interface
* zebra/redistribute.[c,h]: Add new function to propagate link parameters
  to routing daemon (essentially OSPFD and ISISD) for Traffic Engineering.
* zebra/redistribute_null.c: Add new function
  zebra_interface_parameters_update()
* zebra/zserv.[c,h]: Add new functions to send link parameters

Signed-off-by: Olivier Dugeon <olivier.dugeon@orange.com>
diff --git a/zebra/redistribute_null.c b/zebra/redistribute_null.c
index c68cec6..5584d12 100644
--- a/zebra/redistribute_null.c
+++ b/zebra/redistribute_null.c
@@ -78,3 +78,7 @@
                                                 struct connected *b)
 { return; }
 #endif
+
+/* Interface parameters update */
+void zebra_interface_parameters_update (struct interface *ifp)
+{ return; };