Mark some functions with override

Fixes some Clang warnings about overriding a virtual function without the
override keyword.

components/resource/scenemanager.hpp

@@ -141,11 +141,11 @@ namespace Resource
         void setUnRefImageDataAfterApply(bool unref);
 
         /// @see ResourceManager::updateCache
-        virtual void updateCache(double referenceTime);
+        void updateCache(double referenceTime) override;
 
-        virtual void clearCache();
+        void clearCache() override;
 
-        virtual void reportStats(unsigned int frameNumber, osg::Stats* stats) const;
+        void reportStats(unsigned int frameNumber, osg::Stats* stats) const override;
 
     private:
 

components/terrain/chunkmanager.hpp

@@ -32,9 +32,9 @@ namespace Terrain
 
         osg::ref_ptr<osg::Node> getChunk(float size, const osg::Vec2f& center, int lod, unsigned int lodFlags);
 
-        virtual void reportStats(unsigned int frameNumber, osg::Stats* stats) const;
+        void reportStats(unsigned int frameNumber, osg::Stats* stats) const override;
 
-        virtual void clearCache();
+        void clearCache() override;
 
         void releaseGLObjects(osg::State* state) override;