[barcode] PNG output patch

[Alessandro Rubini]

> Would this require checking for availability of intptr_t in the autoconf
> files?  That scares me. :-)
> What about good old void * instead?

Isn't <stdint.h> supposed to be there everywhere?  I tend to prefer
unsigned long or void* myself, but I know it's old-fashioned (yes, I
am) and new standards are the right way to go.

>> Yes. I'd keep Encode_and_Print for postscript output, while using
>> the config step for png.
> 
> Wouldn't an unrolled Barcode_Encode_and_Print (around main.c:546 in my
> patched file) work for all formats?  I might be naive but I don't see
> the need for differentiating paths here.

This allows Barcode_Encode_and_Print to remain alive and tested. The
main.c is meant as an example for users of the library. I agree with your
point, but I think it doesn't apply here.

> But if you prefer to support PNG alone, it's fine with me.

Yes. GIF is irrelevant nowadays and we should let it die, in my opinion.

thanks
/alessandro