Install generated plugin code into the API module.

api/plugins/builtins/tools.go

@@ -0,0 +1,17 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// +build tools
+
+// This file exists to declare that its containing
+// package explicitly depends on the pluginator
+// tool (via go:generate directives)
+package builtins
+
+// TODO: replace this, with the appropriate version
+// once the API is launched, and the new pluginator
+// has been compiled against it and released.
+//
+//  import (
+//  	_ "sigs.k8s.io/kustomize/pluginator"
+// )