fib: implicitly delete empty Entry

Fib::removeNextHopFromAllEntries automatically deletes fib::Entry
if the last nexthop record is being removed.

refs #1341

Change-Id: I36d42fe8f9fc8f03d194f845020aff408cd70488
diff --git a/daemon/table/name-tree-entry.hpp b/daemon/table/name-tree-entry.hpp
index cca1908..e3c72f2 100644
--- a/daemon/table/name-tree-entry.hpp
+++ b/daemon/table/name-tree-entry.hpp
@@ -45,7 +45,7 @@
 /**
  * \brief Name Tree Entry Class
  */
-class Entry : noncopyable
+class Entry : public enable_shared_from_this<Entry>, noncopyable
 {
   // Make private members accessible by Name Tree
   friend class nfd::NameTree;
@@ -80,14 +80,11 @@
   isEmpty() const;
 
   void
-  setFibEntry(shared_ptr<fib::Entry> fib);
+  setFibEntry(shared_ptr<fib::Entry> fibEntry);
 
   shared_ptr<fib::Entry>
   getFibEntry() const;
 
-  bool
-  eraseFibEntry(shared_ptr<fib::Entry> fib);
-
   void
   insertPitEntry(shared_ptr<pit::Entry> pit);