NFD+ndn-cxx: Update version of submodules

- NFD: based on NFD:commit:704430ca07bda92019538b92379c276529efa04a (NFD-0.4.1-1-g704430c)
- ndn-cxx: based on ndn-cxx:commit:2e52d7cab4e03631db7f6c89a2daf7de590dd29e (ndn-cxx-0.4.1)

Note that code compiles, because all ndnSIM code is disabled.  Future
commits re-enable ndnSIM features.

Change-Id: Iff7daad6372eaa719db5af110a842afdcc319978
Refs: #3560
diff --git a/tests/unit-tests/empty.t.cpp b/tests/unit-tests/empty.t.cpp
new file mode 100644
index 0000000..4c56570
--- /dev/null
+++ b/tests/unit-tests/empty.t.cpp
@@ -0,0 +1,36 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2011-2016  Regents of the University of California.
+ *
+ * This file is part of ndnSIM. See AUTHORS for complete list of ndnSIM authors and
+ * contributors.
+ *
+ * ndnSIM is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * ndnSIM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * ndnSIM, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+#include "boost-test.hpp"
+
+namespace ns3 {
+namespace ndn {
+namespace tests {
+
+BOOST_AUTO_TEST_SUITE(Empty)
+
+BOOST_AUTO_TEST_CASE(Nothing)
+{
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace tests
+} // namespace ndn
+} // namespace ns3