lib/time: update to IANA 2013c

This should do it for the release.
There was a new data set pushed out a couple of days ago.

Fixes #4553.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/8621044

lib/time/update.bash

@@ -7,8 +7,8 @@
 # downloaded from the ICANN/IANA distribution.
 
 # Versions to use.
-CODE=2013b
-DATA=2013b
+CODE=2013c
+DATA=2013c
 
 set -e
 rm -rf work