nsync: Change of ndn::ptr_lib to std namespace

Change-Id: I38c3ba68b701709a3a1b41cce327e030a391ba17
Refs: #2110
diff --git a/nsync/sync-logic.h b/nsync/sync-logic.h
index e43a9ac..33578fb 100644
--- a/nsync/sync-logic.h
+++ b/nsync/sync-logic.h
@@ -189,9 +189,9 @@
   LogicRemoveCallback m_onRemove;
   LogicPerBranchCallback m_onUpdateBranch;
   bool m_perBranch;
-  ndn::ptr_lib::shared_ptr<ndn::Validator> m_validator;
-  ndn::ptr_lib::shared_ptr<ndn::KeyChain> m_keyChain;
-  ndn::ptr_lib::shared_ptr<ndn::Face> m_face;
+  std::shared_ptr<ndn::Validator> m_validator;
+  std::shared_ptr<ndn::KeyChain> m_keyChain;
+  std::shared_ptr<ndn::Face> m_face;
   const ndn::RegisteredPrefixId* m_syncRegisteredPrefixId;
 
   ndn::Scheduler m_scheduler;