common: fix NDN_CXX_DECL_FINAL macro

refs #2454

Change-Id: I0bc201fb82d2d44609d2b2b179d94488c8da541b
diff --git a/src/common.hpp b/src/common.hpp
index 1cf0c7b..a4f61e3 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -52,7 +52,7 @@
  */
 #ifdef NDN_CXX_HAVE_CXX_OVERRIDE_FINAL
 #define NDN_CXX_DECL_OVERRIDE override
-#define NDN_CXX_DECL_FINAL override
+#define NDN_CXX_DECL_FINAL final
 #else
 #define NDN_CXX_DECL_OVERRIDE
 #define NDN_CXX_DECL_FINAL