[tz] core dumps on AIX7.1 and HPUX11.31 and tzcode 2017B.

[Kees Dekker]

>It is a lot of work for me to test on HPUX, as I then must rollback my own changes in our product.
>I'm glad to see that there is a fix, and I'm a little bit surprised that you could fix it, even with the minimal description provided by me. Thanks.

I have checked your patch, and have a question:
Why are the (redefines) for tzname, daylight, altzone put under TZ_TIME_T?
Setting TZ_TIME_T has much more effects, and I only like to have 'own' definitions of some variables, but still use the system's time_t type).

Regards,
Kees