Update vendor

vendor/github.com/docker/containerd/supervisor/task.go

@@ -0,0 +1,33 @@
+package supervisor
+
+import (
+	"sync"
+
+	"github.com/docker/containerd/runtime"
+)
+
+// StartResponse is the response containing a started container
+type StartResponse struct {
+	Container runtime.Container
+}
+
+// Task executes an action returning an error chan with either nil or
+// the error from executing the task
+type Task interface {
+	// ErrorCh returns a channel used to report and error from an async task
+	ErrorCh() chan error
+}
+
+type baseTask struct {
+	errCh chan error
+	mu    sync.Mutex
+}
+
+func (t *baseTask) ErrorCh() chan error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.errCh == nil {
+		t.errCh = make(chan error, 1)
+	}
+	return t.errCh
+}