It has been a long time since the last time the vendored zoneinfo in
lib/time was updated, and we're well into the freeze. Update it to the
lastest release from IANA.

Updates #22487

Change-Id: Ib9a8eb409554848285fc88363dbb04ed9d6d9eb0
Reviewed-on: https://go-review.googlesource.com/117855Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>