[eve7] use override specifier for virtual methods

This is more strict declaration, problems faster detected by compiler

graf3d/eve7/inc/ROOT/REveDataSimpleProxyBuilder.hxx

@@ -27,23 +27,22 @@ public:
    virtual ~REveDataSimpleProxyBuilder();
 
 protected:
-   using REveDataProxyBuilderBase::Build;
-   virtual void Build(const REveDataCollection* iCollection, REveElement* product, const REveViewContext*);
-   virtual void BuildViewType(const REveDataCollection* iCollection, REveElement* product, std::string viewType, const REveViewContext*);
+   void Build(const REveDataCollection* iCollection, REveElement* product, const REveViewContext*) override;
+   void BuildViewType(const REveDataCollection* iCollection, REveElement* product, std::string viewType, const REveViewContext*) override;
 
    //called once for each collection in collection, the void* points to the
    // object properly offset in memory
    virtual void Build(const void* data, int index, REveElement* iCollectionHolder, const REveViewContext*) = 0;
    virtual void BuildViewType(const void* data, int index, REveElement* iCollectionHolder, std::string viewType, const REveViewContext*) = 0;
 
-   virtual void Clean();
+   void Clean() override;
 
 private:
    REveDataSimpleProxyBuilder(const REveDataSimpleProxyBuilder&); // stop default
 
    const REveDataSimpleProxyBuilder& operator=(const REveDataSimpleProxyBuilder&); // stop default
 
-   virtual bool VisibilityModelChanges(int idx, REveElement*,  const REveViewContext*);
+   bool VisibilityModelChanges(int idx, REveElement*, const REveViewContext*) override;
 
 };