Fix overlay2 storage driver inside a user namespace

The overlay2 driver was not setting up the archive.TarOptions field
properly like other storage backend routes to "applyTarLayer"
functionality. The InUserNS field is populated now for overlay2 using
the same query function used by the other storage drivers.

Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>

daemon/graphdriver/overlay2/overlay.go

@@ -31,6 +31,7 @@ import (
 	"github.com/docker/docker/pkg/parsers/kernel"
 	"github.com/docker/docker/pkg/system"
 	"github.com/docker/go-units"
+	rsystem "github.com/opencontainers/runc/libcontainer/system"
 	"github.com/opencontainers/selinux/go-selinux/label"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
@@ -704,6 +705,7 @@ func (d *Driver) ApplyDiff(id string, parent string, diff io.Reader) (size int64
 		UIDMaps:        d.uidMaps,
 		GIDMaps:        d.gidMaps,
 		WhiteoutFormat: archive.OverlayWhiteoutFormat,
+		InUserNS:       rsystem.RunningInUserNS(),
 	}); err != nil {
 		return 0, err
 	}