Add fallback for windows platforms without osversion

The background for this change:

1. Windows host-process containers do not have an OS version set
2. Buildx v0.10 started pushing manifest lists by default, but it never
   has the OSVersion in the platform data (not that there is any way to
   specify what particular OS version you want). The change means that
   containerd cannot run images created with the new buildx on Windows
   because there is no matching OSVersion in the list of manifests.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit 8442521)
Signed-off-by: Brian Goff <cpuguy83@gmail.com>

platforms/defaults_windows.go

@@ -46,10 +46,14 @@ type matchComparer struct {
 
 // Match matches platform with the same windows major, minor
 // and build version.
-func (m matchComparer) Match(p imagespec.Platform) bool {
-	if m.defaults.Match(p) {
-		// TODO(windows): Figure out whether OSVersion is deprecated.
-		return strings.HasPrefix(p.OSVersion, m.osVersionPrefix)
+func (m matchComparer) Match(p specs.Platform) bool {
+	match := m.defaults.Match(p)
+
+	if match && p.OS == "windows" {
+		if strings.HasPrefix(p.OSVersion, m.osVersionPrefix) {
+			return true
+		}
+		return p.OSVersion == ""
 	}
 	return false
 }

platforms/defaults_windows_test.go

@@ -104,7 +104,7 @@ func TestMatchComparerMatch(t *testing.T) {
 				Architecture: "amd64",
 				OS:           "windows",
 			},
-			match: false,
+			match: true,
 		},
 	} {
 		assert.Equal(t, test.match, m.Match(test.platform))
@@ -159,11 +159,11 @@ func TestMatchComparerLess(t *testing.T) {
 		{
 			Architecture: "amd64",
 			OS:           "windows",
-			OSVersion:    "10.0.17764.1",
 		},
 		{
 			Architecture: "amd64",
 			OS:           "windows",
+			OSVersion:    "10.0.17764.1",
 		},
 		{
 			Architecture: "amd64",

platforms/platforms_windows_test.go

@@ -19,9 +19,23 @@ package platforms
 import (
 	"testing"
 
+	specs "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/stretchr/testify/require"
 )
 
 func TestNormalize(t *testing.T) {
 	require.Equal(t, DefaultSpec(), Normalize(DefaultSpec()))
 }
+
+func TestFallbackOnOSVersion(t *testing.T) {
+	p := specs.Platform{
+		OS:           "windows",
+		Architecture: "amd64",
+		OSVersion:    "99.99.99.99",
+	}
+
+	other := specs.Platform{OS: p.OS, Architecture: p.Architecture}
+
+	m := NewMatcher(p)
+	require.True(t, m.Match(other))
+}