Fix "unreferenced formal parameter" warning in vtkPolyData::BuildCells()
This fixes the following warning introduced in aac909de (Fix vtkPolyData::GetCell() crash)
warning C4100: 'size': unreferenced formal parameter
This fixes the following warning introduced in aac909de (Fix vtkPolyData::GetCell() crash)
warning C4100: 'size': unreferenced formal parameter