integration: Enable some tests for Windows (part 2)

Some of the tests that are currently running only on Linux can be made
to run on Windows with a few changes.

Signed-off-by: Claudiu Belu <cbelu@cloudbasesolutions.com>

integration/client/helpers_unix_test.go

@@ -23,6 +23,7 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/containerd/containerd/cio"
 	"github.com/containerd/containerd/containers"
 	"github.com/containerd/containerd/oci"
 	specs "github.com/opencontainers/runtime-spec/specs-go"
@@ -56,3 +57,15 @@ func withExecExitStatus(s *specs.Process, es int) {
 func withExecArgs(s *specs.Process, args ...string) {
 	s.Args = args
 }
+
+func newDirectIO(ctx context.Context, terminal bool) (*directIO, error) {
+	fifos, err := cio.NewFIFOSetInDir("", "", terminal)
+	if err != nil {
+		return nil, err
+	}
+	dio, err := cio.NewDirectIO(ctx, fifos)
+	if err != nil {
+		return nil, err
+	}
+	return &directIO{DirectIO: *dio}, nil
+}