Re: tzset: add native Windows workaround

[Bruno Haible]

Ken Brown wrote:
> ... Here's what I see on my Cygwin system:
> 
> $ echo $TZ
> America/New_York
> 
> $ date +'%Y-%m-%d %H:%M:%S %z (%Z)'
> 2017-05-03 07:29:03 -0400 (EDT)
> 
> $ TZ= date +'%Y-%m-%d %H:%M:%S %z (%Z)'
> 2017-05-03 11:29:14 +0000 (GMT)
> 
> $ unset TZ
> 
> $ date +'%Y-%m-%d %H:%M:%S %z (%Z)'
> 2017-05-03 07:29:30 -0400 (EDT)

Thanks for correcting me. I had (incorrectly) assumed that an unset value
and an empty value are equivalent, like for LANG.

I've now brought up the issue on the Cygwin mailing list:
  <https://cygwin.com/ml/cygwin/2017-05/msg00122.html>
Let's see...

Bruno