chacha20poly1305: fix amd64 assembly - replace PINSRB and PEXTRQ
chacha20poly1305: fix amd64 assembly - replace PINSRB and PEXTRQ

The SSE code of chacha20poly1305 used PINSRB and PEXTRQ, which are only available
on machines supporting SSE4.1.

Fixes golang/go#17464

Change-Id: Ic7313433cb21f9a3709d23b50ab58ac1d87957af
Reviewed-on: https://go-review.googlesource.com/31187
Reviewed-by: Adam Langley <db68fba232b2c49ed3e9d3081df349dde7b61dfd@golang.org>
Run-TryBot: Adam Langley <db68fba232b2c49ed3e9d3081df349dde7b61dfd@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

golang/crypto,ScriptRock/crypto,golang/crypto,ScriptRock/crypto,golang/crypto