Replace all uses of BOOST_THROW_EXCEPTION with NDN_THROW

Refs: #4834
Change-Id: I1f9a614c83954873888d13c7b2b17a4fbff81058
diff --git a/tools/ndnsec/util.cpp b/tools/ndnsec/util.cpp
index 5e5c341..1a4b8f4 100644
--- a/tools/ndnsec/util.cpp
+++ b/tools/ndnsec/util.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2019 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -75,7 +75,7 @@
     cert = io::load<security::v2::Certificate>(fileName);
 
   if (cert == nullptr) {
-    BOOST_THROW_EXCEPTION(CannotLoadCertificate(fileName));
+    NDN_THROW(CannotLoadCertificate(fileName));
   }
   return *cert;
 }