Revert recent change with TIFFdOpen -- it breaks subimage appending.
Revert recent change with TIFFdOpen -- it breaks subimage appending.

lgritz/oiio,sambler/oiio,bdeluca/oiio,mcanthony/oiio,cwilling/oiio,scott-wilson/oiio,OpenImageIO/oiio,lgritz/oiio,sambler/oiio,cwilling/oiio,mcanthony/oiio,scott-wilson/oiio,YangYangTL/oiio,YangYangTL/oiio,scott-wilson/oiio,bdeluca/oiio,mcanthony/oiio,OpenImageIO/oiio,bdeluca/oiio,OpenImageIO/oiio,YangYangTL/oiio,micler/oiio,lgritz/oiio,micler/oiio,micler/oiio,YangYangTL/oiio,sambler/oiio,bdeluca/oiio,cwilling/oiio,lgritz/oiio,sambler/oiio,mcanthony/oiio,cwilling/oiio,scott-wilson/oiio,OpenImageIO/oiio,micler/oiio