mgmt: ndns-add-rr-from-file update RR to the latest version

Change-Id: Ia6812e5961bdc885e92cd49fafe2298390667040
Refs: #2259
diff --git a/src/mgmt/management-tool.hpp b/src/mgmt/management-tool.hpp
index 54a1407..69fd355 100644
--- a/src/mgmt/management-tool.hpp
+++ b/src/mgmt/management-tool.hpp
@@ -225,6 +225,11 @@
   bool
   matchCertificate(const Name& certName, const Name& identity);
 
+  /** @brief determine whether an older version of the rrset exists
+   */
+  void
+  checkRrsetVersion(const Rrset& rrset);
+
 private:
   KeyChain& m_keyChain;
   DbMgr m_dbMgr;