NAME
        ClearRectRegion -- Perform 2d CLEAR operation of rectangle
                        with region, leaving result in region.

   SYNOPSIS
        status = ClearRectRegion(region,rectangle)
         d0                       a0      a1

        bool clearrectregion(struct region *, struct rectangle * );

   FUNCTION
        Clip away any portion of the region that exists inside
        of the rectangle. Leave the result in region.

   INPUTS
        region - pointer to region structure
        rectangle - pointer to rectangle structure

   RESULTS
        status - return TRUE if successful operation
                 return FALSE if ran out of memory

   BUGS

   SEE ALSO
        andrectregion() graphics/regions.h