cases: skip tests if unicode.Version does not match UnicodeVersion

For golang/go#11811.
Fixes golang/go#11927.

Change-Id: Ie60c687ba93aaeb6c164413289f474be63e0224f
Reviewed-on: https://go-review.googlesource.com/13252
Reviewed-by: Robert Griesemer <gri@golang.org>
1 file changed