add optional check that snapshotter supports the image platform when unpacking

Signed-off-by: Kathryn Baldauf <kabaldau@microsoft.com>

snapshots/windows/windows.go

@@ -32,10 +32,12 @@ import (
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/log"
 	"github.com/containerd/containerd/mount"
+	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/snapshots"
 	"github.com/containerd/containerd/snapshots/storage"
 	"github.com/containerd/continuity/fs"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 )
 
@@ -44,6 +46,7 @@ func init() {
 		Type: plugin.SnapshotPlugin,
 		ID:   "windows",
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			ic.Meta.Platforms = []ocispec.Platform{platforms.DefaultSpec()}
 			return NewSnapshotter(ic.Root)
 		},
 	})