vendor containers/image for parallel copying of layers

Vendor the latest containers/image 50e5e55e46a391df8fce1291b2337f1af879b822
to enable parallel copying of layers.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

vendor/golang.org/x/sys/unix/sockcmsg_unix.go

@@ -2,36 +2,23 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
 
 // Socket control messages
 
 package unix
 
-import (
-	"runtime"
-	"unsafe"
-)
+import "unsafe"
 
 // Round the length of a raw sockaddr up to align it properly.
 func cmsgAlignOf(salen int) int {
-	salign := SizeofPtr
-
-	switch runtime.GOOS {
-	case "darwin", "dragonfly", "solaris":
-		// NOTE: It seems like 64-bit Darwin, DragonFly BSD and
-		// Solaris kernels still require 32-bit aligned access to
-		// network subsystem.
-		if SizeofPtr == 8 {
-			salign = 4
-		}
-	case "openbsd":
-		// OpenBSD armv7 requires 64-bit alignment.
-		if runtime.GOARCH == "arm" {
-			salign = 8
-		}
+	salign := sizeofPtr
+	// NOTE: It seems like 64-bit Darwin, DragonFly BSD and
+	// Solaris kernels still require 32-bit aligned access to
+	// network subsystem.
+	if darwin64Bit || dragonfly64Bit || solaris64Bit {
+		salign = 4
 	}
-
 	return (salen + salign - 1) & ^(salign - 1)
 }