Add support for Symbian ICL to QS60PixmapData

On non-hardware accelerated devices, Qt is normally configured to use the raster graphics system. The backend for QPixmap on this platform is QS60PixmapData and this class stores data in a CFbsBitmap.

There are 2 function in the base class (QPixmapData) that should be optimized to use the Symbian ICL wherever possible:

    virtual bool fromFile(const QString &filename, const char *format,
                          Qt::ImageConversionFlags flags);
    virtual bool fromData(const uchar *buffer, uint len, const char *format,
                          Qt::ImageConversionFlags flags);

Implementing these functions using the ICL should allow direct loading into a CFbsBitmap.