darwin: use the default values for socketRoot variable

Since the /run directory on macOS is read-only, darwin containerd should
use a different directory.  Use the pre-defined default values instead
to avoid this issue.

Fixes: bd908acab ("Use path based unix socket for shims")
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>

runtime/v2/shim/util_unix.go

@@ -30,6 +30,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/containerd/containerd/defaults"
 	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/pkg/dialer"
 	"github.com/containerd/containerd/sys"
@@ -63,7 +64,7 @@ func AdjustOOMScore(pid int) error {
 	return nil
 }
 
-const socketRoot = "/run/containerd"
+const socketRoot = defaults.DefaultStateDir
 
 // SocketAddress returns a socket address
 func SocketAddress(ctx context.Context, socketPath, id string) (string, error) {