[totem] (6 commits) ...backend: Fix some memory leak on missing plugins

[Bastien Nocera <hadess src gnome org>]

Summary of changes:

  518ca96... backend: Check for glsinkbin at runtime (*)
  59ad2f1... backend: Fix warning if glsinkbin plugin is missing (*)
  0079a83... backend: Remove duplicate free of subtitle_uri (*)
  f0bcd3c... backend: Plug memory leaks on exit (*)
  3670175... main: Fix warning on exit if playbin plugin is missing (*)
  27c5364... backend: Fix some memory leak on missing plugins (*)

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