merge branch 'pr-194'

  pkg: system: use Major, Minor and Mkdev from x/sys/unix
  vendor: add golang.org/x/sys@686000749eaec0b8855b8eef5336cf63899fe51d

LGTMs: @cyphar
Closes opencontainers#194

hack/vendor.sh

@@ -125,7 +125,7 @@ clone github.com/opencontainers/runtime-spec v1.0.0
 clone github.com/opencontainers/runtime-tools 2d270b8764c02228eeb13e36f076f5ce6f2e3591
 clone github.com/syndtr/gocapability 2c00daeb6c3b45114c80ac44119e7b8801fdd852
 clone golang.org/x/crypto b8a2a83acfe6e6770b75de42d5ff4c67596675c0 https://github.com/golang/crypto
-clone golang.org/x/sys fb4cac33e3196ff7f507ab9b2d2a44b0142f5b5a https://github.com/golang/sys
+clone golang.org/x/sys 686000749eaec0b8855b8eef5336cf63899fe51d https://github.com/golang/sys
 clone github.com/docker/go-units v0.3.1
 clone github.com/pkg/errors v0.8.0
 clone github.com/apex/log afb2e76037a5f36542c77e88ef8aef9f469b09f8

pkg/system/mknod_linux.go

@@ -50,19 +50,17 @@ func Tarmode(typeflag byte) uint32 {
 // similar to makedev(3).
 func Makedev(major, minor uint64) Dev_t {
 	// These values come from new_envode_dev inside <linux/kdev_t.h>.
-	return Dev_t((minor & 0xff) | (major << 8) | ((minor &^ 0xff) << 12))
+	return Dev_t(unix.Mkdev(uint32(major), uint32(minor)))
 }
 
 // Majordev returns the major device number given a dev_t, similar to major(3).
 func Majordev(device Dev_t) uint64 {
-	// These values come from new_decode_dev() inside <linux/kdev_t.h>.
-	return uint64((device & 0xfff00) >> 8)
+	return uint64(unix.Major(uint64(device)))
 }
 
 // Minordev returns the minor device number given a dev_t, similar to minor(3).
 func Minordev(device Dev_t) uint64 {
-	// These values come from new_decode_dev() inside <linux/kdev_t.h>.
-	return uint64((device & 0xff) | ((device >> 12) & 0xfff00))
+	return uint64(unix.Minor(uint64(device)))
 }
 
 // Mknod is a wrapper around mknod(2).