face: deduplicate multicast UDP socket setup

In preparation for adding IPv6 support.

Change-Id: I5a3be2007f7fecc44915a5d6794093143ce9c0f9
Refs: #4222
diff --git a/daemon/face/udp-factory.hpp b/daemon/face/udp-factory.hpp
index 9e20be4..3f644c4 100644
--- a/daemon/face/udp-factory.hpp
+++ b/daemon/face/udp-factory.hpp
@@ -116,7 +116,7 @@
   shared_ptr<Face>
   createMulticastFace(const udp::Endpoint& localEndpoint,
                       const udp::Endpoint& multicastEndpoint,
-                      const ndn::net::NetworkInterface& netif);
+                      const shared_ptr<const ndn::net::NetworkInterface>& netif);
 
 private:
   /** \brief Create UDP multicast face on \p netif if needed by \p m_mcastConfig