chacha20poly1305: make polyHashADInternal private

For golang/go#18154.

Change-Id: Ieab8bae9cb8be5e2817a87ae62ac0a2218f63dbb
Reviewed-on: https://go-review.googlesource.com/33855
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed