BMP: protect against corroptions with palette indices out of bound (#3435)
BMP: protect against corroptions with palette indices out of bound (#3435)

If the BMP image we're reading declares a certain sized palette, but
then has pixels that contain values outside the range of that palette
size, we would read past the end of arrays.
lgritz/oiio,lgritz/oiio,OpenImageIO/oiio,OpenImageIO/oiio,OpenImageIO/oiio,OpenImageIO/oiio,lgritz/oiio,lgritz/oiio