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/name.hpp b/src/name.hpp
index 890451f..a2efe1b 100644
--- a/src/name.hpp
+++ b/src/name.hpp
@@ -540,6 +540,8 @@
   mutable Block m_wire;
 };
 
+NDN_CXX_DECLARE_WIRE_ENCODE_INSTANTIATIONS(Name);
+
 inline bool
 operator==(const Name& lhs, const Name& rhs)
 {