Do not compile ChronoSync support by default

ChronoSync dependency is now made optional
and is kept for testing purposes only.

Also change sig-type to ecdsa-sha256 in nlsr.conf
as ndn-cxx now has strict checking for it.

refs: #5147

Change-Id: I95c9fb844681ebf2c4e7bbb03cc7796a0795de83
diff --git a/tools/nlsrc.cpp b/tools/nlsrc.cpp
index adeaeee..6c1f064 100644
--- a/tools/nlsrc.cpp
+++ b/tools/nlsrc.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2020,  The University of Memphis,
+ * Copyright (c) 2014-2021,  The University of Memphis,
  *                           Regents of the University of California,
  *                           Arizona Board of Regents.
  *
@@ -24,15 +24,16 @@
 #include "version.hpp"
 #include "src/publisher/dataset-interest-handler.hpp"
 
-#include <ndn-cxx/face.hpp>
 #include <ndn-cxx/data.hpp>
-#include <ndn-cxx/interest.hpp>
 #include <ndn-cxx/encoding/block.hpp>
+#include <ndn-cxx/face.hpp>
+#include <ndn-cxx/interest.hpp>
 #include <ndn-cxx/mgmt/nfd/control-parameters.hpp>
 #include <ndn-cxx/mgmt/nfd/control-response.hpp>
-#include <ndn-cxx/util/segment-fetcher.hpp>
-#include <ndn-cxx/security/key-chain.hpp>
 #include <ndn-cxx/security/command-interest-signer.hpp>
+#include <ndn-cxx/security/key-chain.hpp>
+#include <ndn-cxx/security/signing-helpers.hpp>
+#include <ndn-cxx/util/segment-fetcher.hpp>
 
 #include <iostream>