table: NameTree::findLongestPrefixMatch accepts all table entry types

This simplifies longest prefix match procedures in FIB and StrategyChoice.

refs #3687

Change-Id: I9aa93232124b91bae7890d065337ac9389e8398e
diff --git a/daemon/table/fib.hpp b/daemon/table/fib.hpp
index 0a44166..eb10850 100644
--- a/daemon/table/fib.hpp
+++ b/daemon/table/fib.hpp
@@ -147,8 +147,11 @@
   };
 
 private:
+  /** \tparam K a parameter acceptable to NameTree::findLongestPrefixMatch
+   */
+  template<typename K>
   const Entry&
-  findLongestPrefixMatch(const name_tree::Entry& nte) const;
+  findLongestPrefixMatchImpl(const K& key) const;
 
   void
   erase(name_tree::Entry* nte, bool canDeleteNte = true);