> > > You don't need to put this check into configure, you can just
> > > do the check after mktime() is used.
> >
> > No, we need that info for the output functions that only use localtime.
> > The intent is, to not use DST before 1970 on platforms that don't have
> > mktime for dates before 1970.
>
> You can't do execution time checks in configure. You're going to have to
> do it at run-time.
We do not need any execution time checks for this at all. The objective is
to determine whether mktime works for any results that would be negative.
On AIX and IRIX all calls to mktime for dates before 1970 lead to a result of
-1, and the configure test is supposed to give a define for exactly that behavior.
Andreas