X11: Report CursorMoved when touch event occurs (#1297)

* X11: Report `CursorMoved` when touch event occurs

* Only trigger CursorMoved events for the first touch ID

* Fix testing for current touch events

* Fix first touch logic

src/platform_impl/linux/x11/mod.rs

@@ -199,6 +199,8 @@ impl<T: 'static> EventLoop<T> {
             xi2ext,
             mod_keymap,
             device_mod_state: Default::default(),
+            num_touch: 0,
+            first_touch: None,
         };
 
         // Register for device hotplug events