gtkwindow: remove delete-event idle function on finalize
gtkwindow: remove delete-event idle function on finalize

Heavy duty can prevent this idle function from being called before
the window is destroyed, so make sure that the source is removed
when the window is finalized.

https://bugzilla.gnome.org/show_bug.cgi?id=723771

chergert/gtk,jigpu/gtk,Lyude/gtk-,Lyude/gtk-,davidgumberg/gtk,jadahl/gtk,Lyude/gtk-,Adamovskiy/gtk,ahodesuka/gtk,Sidnioulz/SandboxGtk,grubersjoe/adwaita,jessevdk/gtk,Sidnioulz/SandboxGtk,grubersjoe/adwaita,jigpu/gtk,chergert/gtk,jadahl/gtk,Sidnioulz/SandboxGtk,jessevdk/gtk,Sidnioulz/SandboxGtk,chergert/gtk,chergert/gtk,Sidnioulz/SandboxGtk,ahodesuka/gtk,davidgumberg/gtk,Lyude/gtk-,Adamovskiy/gtk,alexlarsson/gtk,grubersjoe/adwaita,Adamovskiy/gtk,msteinert/gtk,ahodesuka/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,alexlarsson/gtk,alexlarsson/gtk,Adamovskiy/gtk,chergert/gtk,msteinert/gtk,jigpu/gtk,alexlarsson/gtk,Lyude/gtk-,davidgumberg/gtk,Adamovskiy/gtk,jigpu/gtk,Lyude/gtk-,alexlarsson/gtk,grubersjoe/adwaita,davidgumberg/gtk,chergert/gtk,jadahl/gtk,jigpu/gtk,ahodesuka/gtk,jessevdk/gtk,jadahl/gtk,alexlarsson/gtk,grubersjoe/adwaita,davidgumberg/gtk,ahodesuka/gtk,davidgumberg/gtk,msteinert/gtk,jigpu/gtk,grubersjoe/adwaita,ahodesuka/gtk,Lyude/gtk-,jessevdk/gtk,jadahl/gtk,chergert/gtk,jessevdk/gtk,jessevdk/gtk,alexlarsson/gtk,chergert/gtk,jessevdk/gtk,ahodesuka/gtk,jigpu/gtk,grubersjoe/adwaita,jadahl/gtk,msteinert/gtk,jadahl/gtk,Lyude/gtk-,alexlarsson/gtk,msteinert/gtk,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,Adamovskiy/gtk,Adamovskiy/gtk,davidgumberg/gtk,msteinert/gtk,jigpu/gtk,ahodesuka/gtk