Update vendor

vendor/golang.org/x/crypto/chacha20/chacha_arm64.s

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build go1.11 && gc && !purego
 // +build go1.11,gc,!purego
 
 #include "textflag.h"

vendor/golang.org/x/crypto/chacha20/chacha_ppc64le.s

@@ -19,6 +19,7 @@
 // The differences in this and the original implementation are
 // due to the calling conventions and initialization of constants.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 #include "textflag.h"

vendor/golang.org/x/crypto/chacha20/chacha_s390x.s

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc && !purego
 // +build gc,!purego
 
 #include "go_asm.h"