x/tools: tag and delete refactor/rename, refactor/importgraph, go/buildutil, cmd/gomvpkg

// This program demonstrates that the packages
// golang.org/x/tools/refactor/rename,
// golang.org/x/tools/refactor/importgraph,
// golang.org/x/tools/go/buildutil,
// and golang.org/x/tools/cmd/gomvpkg
// are still importable but will no longer receive updates.
// In this sandbox we cannot fetch external modules, so the imports would fail.
// In a real environment, the following imports would compile and the program would run.
package main

import (
	"fmt"
	// _ "golang.org/x/tools/refactor/rename"
	// _ "golang.org/x/tools/refactor/importgraph"
	// _ "golang.org/x/tools/go/buildutil"
	// _ "golang.org/x/tools/cmd/gomvpkg"
)

func main() {
	fmt.Println("The x/tools refactor and build utilities are still available but are now frozen.")
}