secure/precis: Use internal/testtext runner Change-Id: I73658f436dda909986b6a847c54945ec91a39744 Reviewed-on: https://go-review.googlesource.com/30253 Run-TryBot: Marcel van Lohuizen <mpvl@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>