Don't support DC output if pixel callback
Don't support DC output if pixel callback

This is not supported in the current implementation, so skip outputting DC in this case

libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl