nlsrc: adapt to ndn-cxx SegmentFetcher API change

Refs: #2734
Change-Id: I76f1f1a6b95d2df18a8deef545be5027ad6bbc7c
diff --git a/tools/nlsrc.cpp b/tools/nlsrc.cpp
index 3d43a62..d50d6bd 100644
--- a/tools/nlsrc.cpp
+++ b/tools/nlsrc.cpp
@@ -221,7 +221,7 @@
 
   ndn::util::SegmentFetcher::fetch(m_face,
                                    interest,
-                                   ndn::util::DontVerifySegment(),
+                                   m_validator,
                                    std::bind(&Nlsrc::onFetchSuccess<T>,
                                              this, _1, recordLsa),
                                    std::bind(&Nlsrc::onTimeout, this, _1, _2));
diff --git a/tools/nlsrc.hpp b/tools/nlsrc.hpp
index b62cca0..b2e4bf0 100644
--- a/tools/nlsrc.hpp
+++ b/tools/nlsrc.hpp
@@ -26,6 +26,7 @@
 #include <boost/noncopyable.hpp>
 #include <ndn-cxx/face.hpp>
 #include <ndn-cxx/security/key-chain.hpp>
+#include <ndn-cxx/security/validator-null.hpp>
 
 #include <deque>
 #include <map>
@@ -146,6 +147,7 @@
 private:
   ndn::KeyChain m_keyChain;
   ndn::Face& m_face;
+  ndn::ValidatorNull m_validator;
 
   std::deque<std::function<void()>> m_fetchSteps;