platform.h: Clean up attribute comments and add OIIO_RETURN_NONNULL (#2150)
platform.h: Clean up attribute comments and add OIIO_RETURN_NONNULL (#2150)


OpenImageIO/oiio,OpenImageIO/oiio,lgritz/oiio,lgritz/oiio,OpenImageIO/oiio,lgritz/oiio,lgritz/oiio,OpenImageIO/oiio