[gdm] (5 commits) ...Merge branch 'wip/try-harder-to-get-a-login-screen' into 'master'

[Ray Strode <halfline src gnome org>]

Summary of changes:

  2352143... manager: make get_login_window_session_id fail if no login  (*)
  0e9f09d... common: dedupe gdm_get_login_window_session_id (*)
  6574b4f... common: dedupe activate_session_id (*)
  5e737a5... daemon: try harder to get to a login screen at logout (*)
  c221451... Merge branch 'wip/try-harder-to-get-a-login-screen' into 'm

(*) This commit already existed in another branch; no separate mail sent