Carnival Glory has a self service launderette so no point without availability of irons and unlikely it would not have a hairdryer in the toilet area.
Irons not allowed on cruise ships as they are a fire hazard if they are left on - I doubt if Carnival allow these. I would be surprised if there is any cabin that does not have a hair dryer.
Hairdryers on Glory is in your Vanity Desk drawer. Many other answers are at Carnival.com go to bottom of page FAQ.