chunks: stop using non-public NDN_CXX_DECL_FINAL macro

Change-Id: I853a55044164756c51cc1fa7212e9229aed77229
Refs: #3599, #3613
diff --git a/tools/chunks/catchunks/discover-version-fixed.hpp b/tools/chunks/catchunks/discover-version-fixed.hpp
index 31c77db..9925707 100644
--- a/tools/chunks/catchunks/discover-version-fixed.hpp
+++ b/tools/chunks/catchunks/discover-version-fixed.hpp
@@ -57,11 +57,11 @@
    * @brief identify the latest Data version published.
    */
   void
-  run() NDN_CXX_DECL_FINAL;
+  run() final;
 
 private:
   void
-  handleData(const Interest& interest, const Data& data) NDN_CXX_DECL_FINAL;
+  handleData(const Interest& interest, const Data& data) final;
 
 private:
   Exclude m_strayExcludes;