encoding+lp: declare constexpr and noexcept where possible

Change-Id: Icf708af0b77d62d7d8e75527aaf51c7178e47125
diff --git a/src/encoding/encoding-buffer.hpp b/src/encoding/encoding-buffer.hpp
index 9b483c2..1f21379 100644
--- a/src/encoding/encoding-buffer.hpp
+++ b/src/encoding/encoding-buffer.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2017 Regents of the University of California.
+ * Copyright (c) 2013-2018 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -58,7 +58,6 @@
 public:
   explicit
   EncodingImpl(size_t totalReserve = 0, size_t totalFromBack = 0)
-    : Estimator(totalReserve, totalFromBack)
   {
   }
 };