xwayland: Provide fake cursor with subsurfaces

When the cursor position between the Wayland compositor and XWayland diverges
fake the cursor with a subsurface.

This is a workaround for X clients that try to move the cursor explicitly
through X11.

Signed-off-by: Roman Gilg <subdiff@gmail.com>
4 jobs for fake-cursor in 6 minutes and 37 seconds