Fix oiiotool --dumpdata for uint8 pixels (#2124)
Fix oiiotool --dumpdata for uint8 pixels (#2124)

Sloppiness printed uint8 vals as characters themselves intead of
integer values.
lgritz/oiio,OpenImageIO/oiio,lgritz/oiio,lgritz/oiio,OpenImageIO/oiio,lgritz/oiio,OpenImageIO/oiio,OpenImageIO/oiio