publisher: fix encoding bug in routing table publisher

refs: #4453

Change-Id: I03e819e963f0957f3d40ff25e378f2b9b17357b7
diff --git a/src/tlv/routing-table-entry.hpp b/src/tlv/routing-table-entry.hpp
index 176becb..167f63a 100644
--- a/src/tlv/routing-table-entry.hpp
+++ b/src/tlv/routing-table-entry.hpp
@@ -133,6 +133,8 @@
   mutable ndn::Block m_wire;
 };
 
+NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(RoutingTable);
+
 inline RoutingTable::const_iterator
 RoutingTable::begin() const
 {