bug#641: format-time-string %Z does not work, starting with Emacs 22.2

[Drew Adams]

> At the time the function was introduced, the docstring clearly said:
> "The number of options reflects the strftime(3) function."
> http://cvs.savannah.gnu.org/viewvc/emacs/emacs/src/editfns.c?r
> 1=1.67&r2=1.68&pathrev=HEAD
> 
> Two years later Richard rewrote the docstring and that bit 
> disappeared:
> http://cvs.savannah.gnu.org/viewvc/emacs/emacs/src/editfns.c?r
> 1=1.153&r2=1.154&pathrev=HEAD
> 
> It is open to interpretation (or asking him) whether the intent was to
> detach strftime from format-time-string or not.

OK, thanks.

I really don't care which function lets you format a time to produce a timezone
name on Windows. If `format-time-string' continued to do that, that would be
more backward-compatible, but that's not a biggee. It would be fine if it were
some other function  (or some other format key, besides %Z) that provided this
feature. Just so we don't lose all ability to do this.

For the record, I probably will use %z for my application. But I feel
nevertheless that we should continue to provide some way to produce a timezone
name (on Windows), however rudimentary, language-specific, or non-compliant that
name might be.