Update libcontainer to include PRs with fixes to systemd cgroup driver

PR opencontainers/runc#1754 works around an issue in manager.Apply(-1) that
makes Kubelet startup hang when using systemd cgroup driver (by adding a
timeout) and further PR opencontainers/runc#1772 fixes that bug by
checking the proper error status before waiting on the channel.

PR opencontainers/runc#1776 checks whether Delegate works in slices,
which keeps libcontainer systemd cgroup driver working on systemd v237+.

PR opencontainers/runc#1781 makes the channel buffered, so if we time
out waiting on the channel, the updater will not block trying to it
since there are no longer any consumers.

vendor/github.com/opencontainers/runc/libcontainer/user/lookup_unix.go

@@ -15,6 +15,76 @@ const (
 	unixGroupPath  = "/etc/group"
 )
 
+func lookupUser(username string) (User, error) {
+	return lookupUserFunc(func(u User) bool {
+		return u.Name == username
+	})
+}
+
+func lookupUid(uid int) (User, error) {
+	return lookupUserFunc(func(u User) bool {
+		return u.Uid == uid
+	})
+}
+
+func lookupUserFunc(filter func(u User) bool) (User, error) {
+	// Get operating system-specific passwd reader-closer.
+	passwd, err := GetPasswd()
+	if err != nil {
+		return User{}, err
+	}
+	defer passwd.Close()
+
+	// Get the users.
+	users, err := ParsePasswdFilter(passwd, filter)
+	if err != nil {
+		return User{}, err
+	}
+
+	// No user entries found.
+	if len(users) == 0 {
+		return User{}, ErrNoPasswdEntries
+	}
+
+	// Assume the first entry is the "correct" one.
+	return users[0], nil
+}
+
+func lookupGroup(groupname string) (Group, error) {
+	return lookupGroupFunc(func(g Group) bool {
+		return g.Name == groupname
+	})
+}
+
+func lookupGid(gid int) (Group, error) {
+	return lookupGroupFunc(func(g Group) bool {
+		return g.Gid == gid
+	})
+}
+
+func lookupGroupFunc(filter func(g Group) bool) (Group, error) {
+	// Get operating system-specific group reader-closer.
+	group, err := GetGroup()
+	if err != nil {
+		return Group{}, err
+	}
+	defer group.Close()
+
+	// Get the users.
+	groups, err := ParseGroupFilter(group, filter)
+	if err != nil {
+		return Group{}, err
+	}
+
+	// No user entries found.
+	if len(groups) == 0 {
+		return Group{}, ErrNoGroupEntries
+	}
+
+	// Assume the first entry is the "correct" one.
+	return groups[0], nil
+}
+
 func GetPasswdPath() (string, error) {
 	return unixPasswdPath, nil
 }