gdkwindow: Correct a signature
gdkwindow: Correct a signature

We removed the parameter from callers and from the implementation, but
not from the signature up top. I didn't notice because the branch I was
working on removed the signature entirely.

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