[gdm] (4 commits) Non-fast-forward update to branch wip/fix-some-fd-leaks

[Ray Strode <halfline src gnome org>]

The branch 'wip/fix-some-fd-leaks' 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:

  35e603b... manager: Don't leak session objectso
  29fe076... manager: Clean up user session when finished with display
  c1501e0... session: Don't leak remote greeter interface
  142cd6c... xdmcp-display-factory: Clear launch environment when done w

Commits added to the branch:

  d145871... manager: Don't leak session objects
  1bec912... manager: Clean up user session when finished with display
  26f2a2c... session: Don't leak remote greeter interface
  b6f347a... xdmcp-display-factory: Clear launch environment when done w