[Prolog-standard] max_integer flag on unbounded system

Hi Ulrich,

Quick one about current_prolog_flag/2 when a standard flag is conditionally absent. On a system with bigints, flags max_integer and min_integer are not present. So what should

?- current_prolog_flag(max_integer, X).

do there: fail, or raise domain_error(prolog_flag, max_integer)?

At least Scryer (I've not checked other compliant systems) fails.

Thanks,