The 'tablet_tool_frame' function treats the button masks as though they
are zero-indexed, but 'tablet_tool_button_state' treats them as one-
indexed. The result is that an e.g. middle click event recieved from
Wayland will be sent from the X server as a right-click instead.
Fixes: 773b04748d ("xwayland: handle button events after motion events")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>