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/tests/test-statistics.cpp b/tests/test-statistics.cpp
index 0000fb0..2c02bb7 100644
--- a/tests/test-statistics.cpp
+++ b/tests/test-statistics.cpp
@@ -26,6 +26,7 @@
 #include "nlsr.hpp"
 
 #include <ndn-cxx/util/dummy-client-face.hpp>
+#include <boost/lexical_cast.hpp>
 
 namespace nlsr {
 namespace test {