[gdm] (6 commits) Non-fast-forward update to branch wip/weak-ref-removal

[Ray Strode <halfline src gnome org>]

The branch 'wip/weak-ref-removal' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  ffab477... libgdm: drop support for serializing multiple opens
  01191bf... libgdm: fix pointer/boolean task confusion
  8505c19... libgdm: don't keep manager proxy around longer than we need
  431bdf5... libgdm: get connection explicitly
  1d9c018... libgdm: Drop weak refs on the GDBusConnection

Commits added to the branch:

  993c921... libgdm: drop support for serializing multiple opens
  7138300... libgdm: fix pointer/boolean task confusion
  fb5929e... libgdm: don't keep manager proxy around longer than we need
  402e25b... libgdm: use g_object_unref instead of g_clear_object for we
  0be3d17... libgdm: get connection explicitly
  e5593c5... libgdm: Drop weak refs on the GDBusConnection