blake2b: test all three hashing implementations

This adds use* flags for all arches so a common test can observe what
implementations are supported and test all supported implementations.

Change-Id: I0497b91294ed99309074ac4614ac996e006630c5
Reviewed-on: https://go-review.googlesource.com/31714
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Andreas Auernhammer <aead@mail.de>
3 files changed