linux: Honor RuncOptions if set on container

This also fix the type used for RuncOptions.SystemCgroup, hence introducing
an API break.

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

container_linux_test.go

@@ -851,3 +851,48 @@ func TestDaemonRestartWithRunningShim(t *testing.T) {
 		t.Errorf("pid %d still exists", pid)
 	}
 }
+
+func TestContainerRuntimeOptions(t *testing.T) {
+	t.Parallel()
+
+	client, err := newClient(t, address)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer client.Close()
+
+	var (
+		image       Image
+		ctx, cancel = testContext()
+		id          = t.Name()
+	)
+	defer cancel()
+
+	image, err = client.GetImage(ctx, testImage)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	container, err := client.NewContainer(
+		ctx, id,
+		WithNewSpec(withImageConfig(image), withExitStatus(7)),
+		withNewSnapshot(id, image),
+		WithRuntime("io.containerd.runtime.v1.linux", &runcopts.RuncOptions{Runtime: "no-runc"}),
+	)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	defer container.Delete(ctx, WithSnapshotCleanup)
+
+	task, err := container.NewTask(ctx, empty())
+	if err == nil {
+		t.Errorf("task creation should have failed")
+		task.Delete(ctx)
+		return
+	}
+	if !strings.Contains(err.Error(), `"no-runc"`) {
+		t.Errorf("task creation should have failed because of lack of executable. Instead failed with: %v", err.Error())
+	}
+}