Session logged in from cdm not active in utmp

[andres-erbsen]

CDM proccess pid is added to utmp (logged in users file), but after CDM starts the X session and exits, the user does not appear to be logged in anymore. The conventional solution to this seems to be starting user session on the same pid using exec, but this tends to leave the initial tty vulnerable to tampering after using CTRL + C (even if the X session may be locked).

This makes "w", "who" and "users" commands not report the user and "last" shows the duration of cdm menu being displayed as session duration.