DPX input: Comment out assertions (#3674)
DPX input: Comment out assertions (#3674)

We shouldn't abort here, we should return and handle the error better
(which we do).
lgritz/oiio,lgritz/oiio,lgritz/oiio,lgritz/oiio,OpenImageIO/oiio,OpenImageIO/oiio,OpenImageIO/oiio,OpenImageIO/oiio