vendor golang.org/x/crypto using glide

This would help us build go-mtree on RHEL/CentOS and
distros where golang.org/x/crypto isn't provided or supported.

Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org>

vendor/golang.org/x/crypto/blake2s/blake2s_ref.go

@@ -0,0 +1,18 @@
+// 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,!386 gccgo appengine
+
+package blake2s
+
+var (
+	useSSE4    = false
+	useSSSE3   = false
+	useSSE2    = false
+	useGeneric = true
+)
+
+func hashBlocks(h *[8]uint32, c *[2]uint32, flag uint32, blocks []byte) {
+	hashBlocksGeneric(h, c, flag, blocks)
+}