src: drop 'virtual' from functions marked 'final' or 'override'

Change-Id: Ieb6df864ab82f77b2bee9e83aa0bfa2005715950
Refs: #3857
diff --git a/src/util/in-memory-storage-lfu.hpp b/src/util/in-memory-storage-lfu.hpp
index d866a29..8a21d4c 100644
--- a/src/util/in-memory-storage-lfu.hpp
+++ b/src/util/in-memory-storage-lfu.hpp
@@ -51,24 +51,24 @@
    *  frequently accessed Data packet
    *  @return{ whether the Data was removed }
    */
-  virtual bool
+  bool
   evictItem() override;
 
   /** @brief Update the entry when the entry is returned by the find() function,
    *  increment the frequency according to LFU
    */
-  virtual void
+  void
   afterAccess(InMemoryStorageEntry* entry) override;
 
   /** @brief Update the entry after a entry is successfully inserted, add it to the cleanupIndex
    */
-  virtual void
+  void
   afterInsert(InMemoryStorageEntry* entry) override;
 
   /** @brief Update the entry or other data structures before a entry is successfully erased,
    *  erase it from the cleanupIndex
    */
-  virtual void
+  void
   beforeErase(InMemoryStorageEntry* entry) override;
 
 private: