[m-rev.] for review: Handle argv[0] == NULL.

[Peter Wang]

On Mon, 31 Jan 2022 13:52:30 +1100 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> 
> 2022-01-31 13:48 GMT+11:00 "Peter Wang" <novalazy at gmail.com>:
> > @@ -11551,7 +11551,7 @@ system_temp_dir("", 0, !IO).
> >      [will_not_call_mercury, promise_pure, tabled_for_io, thread_safe,
> >          does_not_affect_liveness, may_not_duplicate],
> >  "
> > -    if (MR_progname) {
> > +    if (MR_progname && MR_progname_is_known) {
> >          MR_make_aligned_string(PrognameOut, MR_progname);
> >      } else {
> 
> This is not new, but the first test should be "(MR_progname != NULL)".
> The rest of the diff is fine.

Done. Thanks.

Peter