Move to blake2b-simd due to perf problems in golang.org/x/crypto

Ref https://github.com/golang/go/issues/18563

vendor/golang.org/x/crypto/blake2b/blake2b_ref.go

@@ -1,11 +0,0 @@
-// Copyright 2016 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build !amd64 appengine gccgo
-
-package blake2b
-
-func hashBlocks(h *[8]uint64, c *[2]uint64, flag uint64, blocks []byte) {
-	hashBlocksGeneric(h, c, flag, blocks)
-}