vendor: update buildkit to 8397d0b9

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

vendor/github.com/moby/buildkit/session/filesync/diffcopy_windows.go

@@ -0,0 +1,21 @@
+//go:build windows
+// +build windows
+
+package filesync
+
+import (
+	"github.com/Microsoft/go-winio"
+	"github.com/pkg/errors"
+	"github.com/tonistiigi/fsutil"
+)
+
+func sendDiffCopy(stream Stream, fs fsutil.FS, progress progressCb) error {
+	// adding one SeBackupPrivilege to the process so as to be able
+	// to run the subsequent goroutines in fsutil.Send that need
+	// to copy over special Windows metadata files.
+	// TODO(profnandaa): need to cross-check that this cannot be
+	// exploited in any way.
+	winio.EnableProcessPrivileges([]string{winio.SeBackupPrivilege})
+	defer winio.DisableProcessPrivileges([]string{winio.SeBackupPrivilege})
+	return errors.WithStack(fsutil.Send(stream.Context(), stream, fs, progress))
+}