Use complete_with_cancellable() in file enumerator
Use complete_with_cancellable() in file enumerator

This makes sure we always return ERROR_CANCELLED, just like we want to
guarantee and avoids crashes in the file chooser.

https://bugzilla.gnome.org/show_bug.cgi?id=614099

halfline/gvfs,gicmo/gvfs,philipl/gvfs,xkahn/gvfs-cmis,xkahn/gvfs-cmis,halfline/gvfs,philipl/gvfs,cpatulea/gvfs,xkahn/gvfs-cmis,cpatulea/gvfs,gicmo/gvfs,xkahn/gvfs-cmis,halfline/gvfs,gicmo/gvfs,philipl/gvfs,gicmo/gvfs