[m-rev.] for review: add system_error_is_success/1

[Julien Fischer]

On Mon, 13 Feb 2023, Peter Wang wrote:

> On Sun, 12 Feb 2023 20:48:49 +1100 Julien Fischer <jfischer at opturion.com> wrote:
>>
>> For review by anyone.
>>
>> ----------------------
>>
>> Add system_error_is_success/1.
>>
>> library/io.m:
>>       As above.
>>
>> library/io.error_util.m:
>>       Delete the equivalent operation is_success/1 from here and
>>       just use system_error_is_success/1 instead.
>>
>> NEWS.md:
>>       Announce the new predicate.
>>

Thanks Peter!

Julien.