Support for multi-arch image unpacking

Resolves the platform on multi-arch manifests during unpack and config resolving.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

container_opts_unix.go

@@ -12,6 +12,7 @@ import (
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/platforms"
 	"github.com/gogo/protobuf/proto"
 	protobuf "github.com/gogo/protobuf/types"
 	digest "github.com/opencontainers/go-digest"
@@ -38,7 +39,7 @@ func WithCheckpoint(desc v1.Descriptor, snapshotKey string) NewContainerOpts {
 				fk := m
 				rw = &fk
 			case images.MediaTypeDockerSchema2Manifest:
-				config, err := images.Config(ctx, store, m)
+				config, err := images.Config(ctx, store, m, platforms.Format(platforms.Default()))
 				if err != nil {
 					return err
 				}