Add VirtualLightRefBase

    mutable volatile int32_t mCount;

};

// This is a wrapper around LightRefBase that simply enforces a virtual

// destructor to eliminate the template requirement of LightRefBase

class VirtualLightRefBase : public LightRefBase<VirtualLightRefBase> {

public:

    virtual ~VirtualLightRefBase() {}

};

// ---------------------------------------------------------------------------

template <typename T>