util: hide MonotonicDeadlineTimer into detail

refs #3940

Change-Id: Ied9ebf58812ade64b13f7647b8e2cafc4c383997
diff --git a/src/util/time-unit-test-clock.cpp b/src/util/time-unit-test-clock.cpp
index 7ed848d..58e1f03 100644
--- a/src/util/time-unit-test-clock.cpp
+++ b/src/util/time-unit-test-clock.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2014 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).
  *
@@ -20,7 +20,7 @@
  */
 
 #include "time-unit-test-clock.hpp"
-#include "monotonic_deadline_timer.hpp"
+#include "detail/monotonic-deadline-timer.hpp"
 #include <thread>
 
 namespace ndn {