vendor: add buildkit

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

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

@@ -0,0 +1,40 @@
+// +build windows
+
+package user
+
+import (
+	"fmt"
+	"os/user"
+)
+
+func lookupUser(username string) (User, error) {
+	u, err := user.Lookup(username)
+	if err != nil {
+		return User{}, err
+	}
+	return userFromOS(u)
+}
+
+func lookupUid(uid int) (User, error) {
+	u, err := user.LookupId(fmt.Sprintf("%d", uid))
+	if err != nil {
+		return User{}, err
+	}
+	return userFromOS(u)
+}
+
+func lookupGroup(groupname string) (Group, error) {
+	g, err := user.LookupGroup(groupname)
+	if err != nil {
+		return Group{}, err
+	}
+	return groupFromOS(g)
+}
+
+func lookupGid(gid int) (Group, error) {
+	g, err := user.LookupGroupId(fmt.Sprintf("%d", gid))
+	if err != nil {
+		return Group{}, err
+	}
+	return groupFromOS(g)
+}