evdev: Add ABS_MT_* support for direct touch devices

This adds ABS_MT_* support for direct touch devices and notifies
the compositor.  The compositor has a stub for now.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
diff --git a/compositor/compositor.c b/compositor/compositor.c
index 844d59d..384f79e 100644
--- a/compositor/compositor.c
+++ b/compositor/compositor.c
@@ -1437,6 +1437,18 @@
 	}
 }
 
+/**
+ * notify_touch - emulates button touches and notifies surfaces accordingly.
+ *
+ * It assumes always the correct cycle sequence until it gets here: touch_down
+ * → touch_update → ... → touch_update → touch_end. The driver is responsible
+ * for sending along such order.
+ */
+WL_EXPORT void
+notify_touch(struct wl_input_device *device, uint32_t time, int touch_id,
+             int x, int y, int touch_type)
+{
+}
 
 static void
 input_device_attach(struct wl_client *client,