Upgrade the underlying NFD and ndn-cxx to version 0.6.1 and fixing compilation

Specific changes:

1) model: NetDeviceTransport uses the MTU of NS-3 netDevice
2) utils: Adapting to the updates of the ndn-cxx CustomClock abstraction

Change-Id: Ic0dba06a9afd66a810172d4a512f35f6df6b222a
Refs: #4471, #4514
diff --git a/.gitmodules b/.gitmodules
index eda145d..fb3347b 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,8 @@
 [submodule "NFD"]
 	path = NFD
 	url = https://github.com/named-data-ndnSIM/NFD
+	branch = NFD-0.6.1-ndnSIM
 [submodule "ndn-cxx"]
 	path = ndn-cxx
 	url = https://github.com/named-data-ndnSIM/ndn-cxx
+	branch = ndn-cxx-0.6.1-ndnSIM
diff --git a/NFD b/NFD
index 9253fad..3bebd11 160000
--- a/NFD
+++ b/NFD
@@ -1 +1 @@
-Subproject commit 9253fad76a7d90670d9822b7dca655e45c99b70e
+Subproject commit 3bebd1190b1c45f8acaa0fe1d3a3100651a062e4
diff --git a/model/ndn-net-device-transport.cpp b/model/ndn-net-device-transport.cpp
index 2d946c8..32abaa6 100644
--- a/model/ndn-net-device-transport.cpp
+++ b/model/ndn-net-device-transport.cpp
@@ -47,7 +47,7 @@
   this->setScope(scope);
   this->setPersistency(persistency);
   this->setLinkType(linkType);
-  // this->setMtu(udp::computeMtu(m_socket.local_endpoint())); // not sure what should be here
+  this->setMtu(m_netDevice->GetMtu()); // Use the MTU of the netDevice
 
   NS_LOG_FUNCTION(this << "Creating an ndnSIM transport instance for netDevice with URI"
                   << this->getLocalUri());
diff --git a/ndn-cxx b/ndn-cxx
index d593f6a..e1ae096 160000
--- a/ndn-cxx
+++ b/ndn-cxx
@@ -1 +1 @@
-Subproject commit d593f6ab52fbc306488b495054a695ec592a1039
+Subproject commit e1ae096efd8ad503ce7dbd616ee174afaed6c66b
diff --git a/utils/ndn-time.cpp b/utils/ndn-time.cpp
index 717acde..f4a5955 100644
--- a/utils/ndn-time.cpp
+++ b/utils/ndn-time.cpp
@@ -38,11 +38,11 @@
   return " since start of simulation";
 }
 
-boost::posix_time::time_duration
-CustomSystemClock::toPosixDuration(const system_clock::duration& duration) const
+system_clock::duration
+CustomSystemClock::toWaitDuration(system_clock::duration d) const
 {
   BOOST_ASSERT_MSG(false, "Must not be called");
-  return boost::posix_time::microseconds(1);
+  return time::microseconds(1);
 }
 
 ////////////////////////////////////
@@ -60,11 +60,11 @@
   return " since start of simulation";
 }
 
-boost::posix_time::time_duration
-CustomSteadyClock::toPosixDuration(const steady_clock::duration& duration) const
+steady_clock::duration
+CustomSteadyClock::toWaitDuration(steady_clock::duration d) const
 {
   BOOST_ASSERT_MSG(false, "Must not be called");
-  return boost::posix_time::microseconds(1);
+  return time::microseconds(1);
 }
 
 } // namespace time
diff --git a/utils/ndn-time.hpp b/utils/ndn-time.hpp
index d07c86e..7839f50 100644
--- a/utils/ndn-time.hpp
+++ b/utils/ndn-time.hpp
@@ -36,8 +36,8 @@
   std::string
   getSince() const;
 
-  boost::posix_time::time_duration
-  toPosixDuration(const system_clock::duration& duration) const;
+  system_clock::duration
+  toWaitDuration(system_clock::duration d) const;
 };
 
 class CustomSteadyClock : public CustomClock<steady_clock> {
@@ -48,8 +48,8 @@
   std::string
   getSince() const;
 
-  boost::posix_time::time_duration
-  toPosixDuration(const steady_clock::duration& duration) const;
+  steady_clock::duration
+  toWaitDuration(steady_clock::duration d) const;
 };
 
 } // namespace time