face: override Transport::beforeChangePersistency in all subclasses

This commit also adds the final specifier to some Transport
subclasses in order to improve code generation.

Change-Id: If2979fa1614476a98019ba79cee3961663fc447b
Refs: #3318
diff --git a/daemon/face/internal-transport.hpp b/daemon/face/internal-transport.hpp
index a282638..53bd379 100644
--- a/daemon/face/internal-transport.hpp
+++ b/daemon/face/internal-transport.hpp
@@ -63,6 +63,9 @@
 
 protected:
   virtual void
+  beforeChangePersistency(ndn::nfd::FacePersistency newPersistency) DECL_OVERRIDE;
+
+  virtual void
   doClose() DECL_OVERRIDE;
 
 private: