language: update with latest IANA data Change-Id: Ib46b8e3d27c797eae6a00ab11d69733bd35eacb8 Reviewed-on: https://go-review.googlesource.com/30872 Run-TryBot: Marcel van Lohuizen <mpvl@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Nigel Tao <nigeltao@golang.org>