Fixes #399 Adds wlr_data_device_manager destructor

Fixed issues

include/wlr/types/wlr_data_device.h

@@ -74,6 +74,11 @@ struct wlr_drag {
 struct wlr_data_device_manager *wlr_data_device_manager_create(
 		struct wl_display *display);
 
+/**
+ * Destroys a wlr_data_device_manager and removes its wl_data_device_manager global.
+ */
+void wlr_data_device_manager_destroy(struct wlr_data_device_manager *manager);
+
 /**
  * Creates a new wl_data_offer if there is a wl_data_source currently set as
  * the seat selection and sends it to the seat client, followed by the

types/wlr_data_device.c

@@ -815,3 +815,11 @@ struct wlr_data_device_manager *wlr_data_device_manager_create(
 
 	return manager;
 }
+
+void wlr_data_device_manager_destroy(struct wlr_data_device_manager *manager) {
+  if (!manager) {
+    return;
+  }
+  wl_global_destroy(manager->global);
+  free(manager);
+}