Keep the g_clear_pointer call

Otherwise most tests fail to run. So I added a helper function
that does the proper casting to struct pw_proxy *.

src/pipewire.c

@@ -212,6 +212,11 @@ static GSourceFuncs pipewire_source_funcs =
   pipewire_loop_source_finalize
 };
 
+void pipewire_registry_destroy(struct pw_registry *registry)
+{
+  pw_proxy_destroy((struct pw_proxy *)registry);
+}
+
 void
 pipewire_remote_destroy (PipeWireRemote *remote)
 {
@@ -224,8 +229,7 @@ pipewire_remote_destroy (PipeWireRemote *remote)
   /* This check is a workaround for older PW versions */
   if (remote->registry)
     spa_hook_remove (&remote->registry_listener);
-  pw_proxy_destroy((struct pw_proxy *)remote->registry);
-  remote->registry = NULL;
+  g_clear_pointer (&remote->registry, pipewire_registry_destroy);
   g_clear_pointer (&remote->globals, g_hash_table_destroy);
   if (remote->core)
     spa_hook_remove (&remote->core_listener);