vendor: update buildkit to v0.8

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

vendor/github.com/moby/sys/mountinfo/mounted_unix.go

@@ -0,0 +1,66 @@
+// +build linux freebsd,cgo openbsd,cgo
+
+package mountinfo
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"golang.org/x/sys/unix"
+)
+
+func mountedByStat(path string) (bool, error) {
+	var st unix.Stat_t
+
+	if err := unix.Lstat(path, &st); err != nil {
+		if err == unix.ENOENT {
+			// Treat ENOENT as "not mounted".
+			return false, nil
+		}
+		return false, &os.PathError{Op: "stat", Path: path, Err: err}
+	}
+	dev := st.Dev
+	parent := filepath.Dir(path)
+	if err := unix.Lstat(parent, &st); err != nil {
+		return false, &os.PathError{Op: "stat", Path: parent, Err: err}
+	}
+	if dev != st.Dev {
+		// Device differs from that of parent,
+		// so definitely a mount point.
+		return true, nil
+	}
+	// NB: this does not detect bind mounts on Linux.
+	return false, nil
+}
+
+func normalizePath(path string) (realPath string, err error) {
+	if realPath, err = filepath.Abs(path); err != nil {
+		return "", fmt.Errorf("unable to get absolute path for %q: %w", path, err)
+	}
+	if realPath, err = filepath.EvalSymlinks(realPath); err != nil {
+		return "", fmt.Errorf("failed to canonicalise path for %q: %w", path, err)
+	}
+	if _, err := os.Stat(realPath); err != nil {
+		return "", fmt.Errorf("failed to stat target of %q: %w", path, err)
+	}
+	return realPath, nil
+}
+
+func mountedByMountinfo(path string) (bool, error) {
+	path, err := normalizePath(path)
+	if err != nil {
+		if errors.Is(err, unix.ENOENT) {
+			// treat ENOENT as "not mounted"
+			return false, nil
+		}
+		return false, err
+	}
+	entries, err := GetMounts(SingleEntryFilter(path))
+	if err != nil {
+		return false, err
+	}
+
+	return len(entries) > 0, nil
+}