language: user -u-va-posix instead of -x-posix.

Use CLDR variant. Collate already used this. This provides
a little bit more structure and plays nice with collation.

Note that maketables.go contained a bug that happened to work
given the current data in CLDR.

Change-Id: I40d07d7cd2a8615bbe0e223a074df5b701b7b833
Reviewed-on: https://go-review.googlesource.com/14805
Reviewed-by: Nigel Tao <nigeltao@golang.org>
5 files changed