Vendor in c/image with sigstore support

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/golang.org/x/sys/cpu/cpu_zos.go

@@ -0,0 +1,10 @@
+// Copyright 2020 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.
+
+package cpu
+
+func archInit() {
+	doinit()
+	Initialized = true
+}