Which air transport aircraft have a lavatory included inside the cockpit? Another answer on SE Aviation (Why pilots would leave the cockpit in a short flight?
) had this bit of information in it:


  The cockpit of some airliners lacks a lavatory.


Isn't is more the other way around: i.e. A Lavatory inside a cockpit is a rarity?

Which airliner cockpits have an entire Lavatory inside them? 

I always thought the Flight Crew came out to use the forward-most Business / First class lavatory.
As far as I know, some Boeing 747-400s (BA, Air France) had lavatories inside the cockpit. Apparently, Boeing 747-8 Intercontinental has a lavatory behind the cockpit door:


  ... Lufthansa Boeing 747-8 Intercontinental is unique in that the flight deck crew have their own lavatory, ... behind the locked cockpit door, allowing for extra security and a non-disruptive cabin service involving trolleys blocking the door.