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/src/communication/sync-logic-handler.cpp b/src/communication/sync-logic-handler.cpp
index 99bdeac..4f8eba2 100644
--- a/src/communication/sync-logic-handler.cpp
+++ b/src/communication/sync-logic-handler.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.
  *
@@ -26,6 +26,8 @@
 #include "logger.hpp"
 #include "utility/name-helper.hpp"
 
+#include <boost/lexical_cast.hpp>
+
 namespace nlsr {
 
 INIT_LOGGER(SyncLogicHandler);