The abbreviations list in zoneinfo_abbrs_windows.go was last updated
in June 2017, and it's currently outdated. Update it.

Change-Id: Ie2bf4268787f5aefe98ee110c2c279451e18fd97
Reviewed-on: https://go-review.googlesource.com/120559
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>