lib/time: update tzdata to 2017c

Update the tzdata database to version 2017c (released 2017-10-20).

Updates #22487

Change-Id: If58ff89173ef1f1044075505f42ff132b57795f0
Reviewed-on: https://go-review.googlesource.com/74230Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

lib/time/update.bash

@@ -8,8 +8,8 @@
 # Consult http://www.iana.org/time-zones for the latest versions.
 
 # Versions to use.
-CODE=2017b
-DATA=2017b
+CODE=2017c
+DATA=2017c
 
 set -e
 rm -rf work