route: Add support for MPLS encap

Add support for MPLS lwtunnel encapsulation.

Signed-off-by: David Ahern <dsahern@gmail.com>
diff --git a/libnl-route-3.sym b/libnl-route-3.sym
index 4382775..e66682a 100644
--- a/libnl-route-3.sym
+++ b/libnl-route-3.sym
@@ -1059,4 +1059,5 @@
 	rtnl_route_nh_get_via;
 	rtnl_route_set_ttl_propagate;
 	rtnl_route_get_ttl_propagate;
+	rtnl_route_nh_encap_mpls;
 } libnl_3_2_29;