lib/time: update tz data to 2019b

Updates #22487

Change-Id: I3c933c68b5c3c5e78e3a9656ea2dcdbcbb59533f
Reviewed-on: https://go-review.googlesource.com/c/go/+/184577
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

lib/time/update.bash

@@ -8,8 +8,8 @@
 # Consult https://www.iana.org/time-zones for the latest versions.
 
 # Versions to use.
-CODE=2018i
-DATA=2018i
+CODE=2019b
+DATA=2019b
 
 set -e
 rm -rf work