ui/app: don't use wl_touch interface v6

It's not tested, we don't need v6 capabilities and using them result
in build errors on older wayland clients:

https://www.reddit.com/r/golang/comments/b7rujg/gio_by_elias_naur_et_al_portable_immediate_mode/ejv804z/

Finally, since we request v5 of the parent wl_seat, the wl_touch instances
returned to us is capped at v5 anyway.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/app/os_wayland.c

@@ -104,8 +104,6 @@ static const struct wl_touch_listener wl_touch_listener = {
 	.motion = gio_onTouchMotion,
 	.frame = gio_onTouchFrame,
 	.cancel = gio_onTouchCancel,
-	.shape = gio_onTouchShape,
-	.orientation = gio_onTouchOrientation
 };
 
 void gio_wl_touch_add_listener(struct wl_touch *touch) {

ui/app/os_wayland.go

@@ -474,14 +474,6 @@ func gio_onTouchCancel(data unsafe.Pointer, touch *C.struct_wl_touch) {
 	})
 }
 
-//export gio_onTouchShape
-func gio_onTouchShape(data unsafe.Pointer, touch *C.struct_wl_touch, id C.int32_t, major, minor C.wl_fixed_t) {
-}
-
-//export gio_onTouchOrientation
-func gio_onTouchOrientation(data unsafe.Pointer, touch *C.struct_wl_touch, id C.int32_t, orientation C.wl_fixed_t) {
-}
-
 //export gio_onPointerEnter
 func gio_onPointerEnter(data unsafe.Pointer, pointer *C.struct_wl_pointer, serial C.uint32_t, surf *C.struct_wl_surface, x, y C.wl_fixed_t) {
 	// Get images[0].