wayland: Avoid segfault when cursors are freed
wayland: Avoid segfault when cursors are freed

The check for GDK_CURSOR_IS_PIXMAP was ineffective, since _all_
cursors have this type, from the looks of it. Instead, store
buffer ownership information separately.

jigpu/gtk,jadahl/gtk,ahodesuka/gtk,davidgumberg/gtk,jadahl/gtk,chergert/gtk,Lyude/gtk-,Sidnioulz/SandboxGtk,ahodesuka/gtk,grubersjoe/adwaita,alexlarsson/gtk,bratsche/gtk-,jigpu/gtk,Distrotech/gtk2,ahodesuka/gtk,grubersjoe/adwaita,davidgumberg/gtk,Lyude/gtk-,ebassi/gtk,Distrotech/gtk2,jigpu/gtk,alexlarsson/gtk,alexlarsson/gtk,Adamovskiy/gtk,chergert/gtk,alexlarsson/gtk,Lyude/gtk-,Distrotech/gtk2,jadahl/gtk,jessevdk/gtk,Adamovskiy/gtk,Sidnioulz/SandboxGtk,ebassi/gtk,ahodesuka/gtk,alexlarsson/gtk,alexlarsson/gtk,ahodesuka/gtk,Lyude/gtk-,grubersjoe/adwaita,msteinert/gtk,Adamovskiy/gtk,msteinert/gtk,Lyude/gtk-,davidgumberg/gtk,davidgumberg/gtk,jigpu/gtk,chergert/gtk,Sidnioulz/SandboxGtk,Adamovskiy/gtk,msteinert/gtk,davidgumberg/gtk,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,msteinert/gtk,Adamovskiy/gtk,alexlarsson/gtk,jadahl/gtk,davidgumberg/gtk,chergert/gtk,jigpu/gtk,jigpu/gtk,bratsche/gtk-,Lyude/gtk-,Distrotech/gtk2,jadahl/gtk,grubersjoe/adwaita,davidgumberg/gtk,ebassi/gtk,jessevdk/gtk,davidgumberg/gtk,Lyude/gtk-,chergert/gtk,bratsche/gtk-,Lyude/gtk-,Distrotech/gtk2,bratsche/gtk-,jessevdk/gtk,ebassi/gtk,grubersjoe/adwaita,chergert/gtk,jigpu/gtk,bratsche/gtk-,Adamovskiy/gtk,ebassi/gtk,chergert/gtk,jessevdk/gtk,grubersjoe/adwaita,ahodesuka/gtk,jadahl/gtk,jessevdk/gtk,ahodesuka/gtk,msteinert/gtk,chergert/gtk,grubersjoe/adwaita,bratsche/gtk-,ebassi/gtk,alexlarsson/gtk,jessevdk/gtk,ahodesuka/gtk,Adamovskiy/gtk,jadahl/gtk,Sidnioulz/SandboxGtk,msteinert/gtk,Sidnioulz/SandboxGtk,jigpu/gtk,jessevdk/gtk,Distrotech/gtk2,Sidnioulz/SandboxGtk