Add global flags to all commands and subcommands (#2605)

cmd/update-main.go

@@ -33,10 +33,6 @@ import (
 // command specific flags.
 var (
 	updateFlags = []cli.Flag{
-		cli.BoolFlag{
-			Name:  "help, h",
-			Usage: "Help for update.",
-		},
 		cli.BoolFlag{
 			Name:  "experimental, E",
 			Usage: "Check experimental update.",
@@ -49,7 +45,7 @@ var updateCmd = cli.Command{
 	Name:   "update",
 	Usage:  "Check for a new software update.",
 	Action: mainUpdate,
-	Flags:  updateFlags,
+	Flags:  append(updateFlags, globalFlags...),
 	CustomHelpTemplate: `Name:
    minio {{.Name}} - {{.Usage}}