Fix the JPEG writer's implicit RGBA-to-RGB conversion.  Was getting the strides all wrong. Review by: c42f
Fix the JPEG writer's implicit RGBA-to-RGB conversion.  Was getting the
strides all wrong.
Review by: c42f


git-svn-id: c3edda122e248ef33995da003806c930f62b9468@1696 31904243-a364-42ac-a3db-9305396518ba

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