mir: Fix build failure due to changed API
mir: Fix build failure due to changed API

mir_surface_set_event_handler() now takes three arguments.

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