Add -Wextra-semi -Wundefined-func-template to the default CXXFLAGS

And fix the resulting compilation errors.

Change-Id: I16f679836a0cf2a3ff5dfcf6f6b67bfbfe4cdbd7
Refs: #4248
diff --git a/src/security/safe-bag.hpp b/src/security/safe-bag.hpp
index 12555c9..13a2410 100644
--- a/src/security/safe-bag.hpp
+++ b/src/security/safe-bag.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2016 Regents of the University of California.
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,9 +25,8 @@
 
 #include "../common.hpp"
 #include "../data.hpp"
+#include "../encoding/block.hpp"
 #include "../encoding/buffer.hpp"
-#include "../encoding/encoder.hpp"
-#include "../encoding/encoding-buffer.hpp"
 #include "security-common.hpp"
 
 namespace ndn {
@@ -115,6 +114,8 @@
   mutable Block m_wire;
 };
 
+NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(SafeBag);
+
 } // namespace security
 } // namespace ndn