[AGENT++] Counter64: in hex - TODO of 2002

[Jochen Katz]

Hi,

> this is just a quick hack - but getting Counter64 as hex once they
> overflow 2^32 is a bit unexpected.
> 
> Probably this would need a bit more ifdef spaghetti

we're lucky: The define HAVE_INTTYPES_H is already available, so I can
use it to enable the old code if it is not defined.

Thanks for your report,
  Jochen