DngDecoder::decodeData(): slices: check that slices provide all the pixels.
DngDecoder::decodeData(): slices: check that slices provide all the pixels.

darktable-org/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed