Update gomod and vendor

vendor/github.com/moby/buildkit/worker/result.go

@@ -0,0 +1,40 @@
+package worker
+
+import (
+	"context"
+
+	"github.com/moby/buildkit/cache"
+	"github.com/moby/buildkit/solver"
+)
+
+func NewWorkerRefResult(ref cache.ImmutableRef, worker Worker) solver.Result {
+	return &workerRefResult{&WorkerRef{ImmutableRef: ref, Worker: worker}}
+}
+
+type WorkerRef struct {
+	ImmutableRef cache.ImmutableRef
+	Worker       Worker
+}
+
+func (wr *WorkerRef) ID() string {
+	refID := ""
+	if wr.ImmutableRef != nil {
+		refID = wr.ImmutableRef.ID()
+	}
+	return wr.Worker.ID() + "::" + refID
+}
+
+type workerRefResult struct {
+	*WorkerRef
+}
+
+func (r *workerRefResult) Release(ctx context.Context) error {
+	if r.ImmutableRef == nil {
+		return nil
+	}
+	return r.ImmutableRef.Release(ctx)
+}
+
+func (r *workerRefResult) Sys() interface{} {
+	return r.WorkerRef
+}