It seems that windowsZones.xml file has moved to Github. I opened

http://unicode.org/cldr/data/common/supplemental/windowsZones.xml

in my browser, and it redirected me to

https://github.com/unicode-org/cldr/blob/master/common/supplemental/windowsZones.xml

Very nice of them.

And we could see windowsZones.xml change history now. We could even
probably file issues against this file, if we find problems.

Anyway, this CL adjusts genzabbrs.go to use new GitHub location.

I also run 'go generate' command with updated genzabbrs.go to update
zoneinfo_abbrs_windows.go.

Fixes #34917

Change-Id: I69b71a4e02edd999435738ecb225a6f9793a66d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/201378
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>