unicode/norm: test unused tables are dropped Change-Id: Ie068d74c4c66a7bc38945e3c3b092349fad9d26e Reviewed-on: https://go-review.googlesource.com/36870 Run-TryBot: Marcel van Lohuizen <mpvl@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Nigel Tao <nigeltao@golang.org>