use <stdint.h> to get a really portable 32 bit unsigned type

[DerDakon]

This in turn requires a compiler from the 21st century.

[schmonz]

As usual, I like the change, and am concerned only about timing.

Without this fix, what's at risk? Are there systems that won't compile, systems that'll exhibit surprising runtime behavior, and/or something else entirely?

With this fix, what's at risk? Normally here I'd be concerned about users being able to keep applying their patches, but this one is pretty self-contained. What else should we consider about when is best to merge this?

[DerDakon]

This will not work on systems that do not support C99, as they likely do not have that header. For all other systems using unsigned long at all was IMHO a bad idea, unsigned int is really 32 bit everywhere for ages.