make GetTexHandle() const

stepmania/src/BannerCache.cpp

@@ -130,7 +130,7 @@ BannerCache::~BannerCache()
 struct BannerTexture: public RageTexture
 {
 	unsigned m_uTexHandle;
-	unsigned GetTexHandle() { return m_uTexHandle; };	// accessed by RageDisplay
+	unsigned GetTexHandle() const { return m_uTexHandle; };	// accessed by RageDisplay
 	/* This is a reference to a pointer in m_BannerPathToImage. */
 	SDL_Surface *&img;
 	int width, height;

stepmania/src/RageBitmapTexture.h

@@ -23,7 +23,7 @@ public:
 	/* only called by RageTextureManager::InvalidateTextures */
 	virtual void Invalidate() { m_uTexHandle = 0; /* don't Destroy() */}
 	virtual void Reload();
-	virtual unsigned GetTexHandle() { return m_uTexHandle; };	// accessed by RageDisplay
+	virtual unsigned GetTexHandle() const { return m_uTexHandle; };	// accessed by RageDisplay
 
 private:
 	void Create();	// called by constructor and Reload

stepmania/src/RageTexture.h

@@ -51,7 +51,7 @@ public:
 	virtual void Update( float fDeltaTime ) {}
 	virtual void Reload() {}
 	virtual void Invalidate() { }	/* only called by RageTextureManager::InvalidateTextures */
-	virtual unsigned GetTexHandle() = 0;	// accessed by RageDisplay
+	virtual unsigned GetTexHandle() const = 0;	// accessed by RageDisplay
 
 	// movie texture/animated texture stuff
 	virtual void Play() {}