oiiotool: use functions in ImageBufAlgo rather than duplicating.
oiiotool: use functions in ImageBufAlgo rather than duplicating.

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