and add
BitmapEx::operator=(Bitmap const &)
Image::Image(Bitmap const &)
to lessen the fallout

Change-Id: Iff5fab88d167a7be739c370c9933d36c297bc61c
Reviewed-on: https://gerrit.libreoffice.org/54162Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>