[m-rev.] for review: avoid sprintf when converting integers to strings

[Julien Fischer]

On Fri, 3 Oct 2025 at 16:27, Zoltan Somogyi <zoltan.somogyi at runbox.com> wrote:

> Speed up {int,uint}{,8,16,32,64}_to_string ...
>
> ... when targeting C.
>
> library/string.m:
>     On 27 Oct 2021, Julien speed up one of these operations
>     by avoiding the use of sprintf. Apply the same technique,
>     suitably generalized, to all other similar operations.
>     Use macros to reduce the amount of code duplication needed.
>
> runtime/mercury_conf.h.in:
>     Fix an old bug: spell MR_MERCURY_IS_{32,64}_BITS correctly,
>     to match the name that is (conditionally) defined by configure.
>
> configure.ac:
>     Delete references to MERCURY_IS_{32,64}_BITS, which turn out
>     to be totally unused.

That's fine. It would be possible to make certain cases faster, e.g.
by using the 2 digit lookup table approach with decimals, but that's
probably not so important for now.

Julien.