interest: delete Link and SelectedDelegation fields

They have been replaced by ForwardingHint.

refs #4055

Change-Id: I1d5b5c0f4530af3d8ba2d9a624bb62cf341ccf39
diff --git a/src/link.hpp b/src/link.hpp
index 3fc4387..e358404 100644
--- a/src/link.hpp
+++ b/src/link.hpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
@@ -28,8 +28,6 @@
 
 namespace ndn {
 
-const size_t INVALID_SELECTED_DELEGATION_INDEX = std::numeric_limits<size_t>::max();
-
 /** @brief represents a Link object
  */
 class Link : public Data