Migrate some presubmit functionality to Makefile.

api/internal/tools/tools.go

@@ -0,0 +1,19 @@
+// +build tools
+
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// This file exists to trigger installs of the given tools.
+
+package tools
+
+import (
+	// for code generation
+	_ "golang.org/x/tools/cmd/stringer"
+	// for lint checks
+	_ "github.com/golangci/golangci-lint/cmd/golangci-lint"
+	// for integration tests driven by the examples
+	_ "github.com/monopole/mdrip"
+	// TODO: See comment in Makefile.
+	//_ "sigs.k8s.io/kustomize/pluginator"
+)