Which air transport aircraft have a lavatory included inside the cockpit?
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.