[noise] Noise_IKpsk2_25519_ChaChaPoly_BLAKE2s first message benchmarks

[Jason A. Donenfeld]

Hey Trevor,

On Wed, May 24, 2017 at 2:35 AM, Trevor Perrin <trevp at trevp.net> wrote:
> You've probably thought of this, but another optimization would be for
> the server to cache the ss calculation from the first message:

I had that a long time ago, but then removed it during a refactoring
and never added it back. Thanks for the reminder. The performance now
doubles, as we'd expect.

Jason