Revert "Process-lock is required when changing processors"

This reverts commit 0a213e71b3.
which needs a better solution to prevent deadlock in case the lock is
already taken.

libs/ardour/track.cc

@@ -106,7 +106,6 @@ Track::init ()
 	 */
 
 	if (!is_auditioner()) {
-		Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
 		boost::shared_ptr<TriggerBox> tb (new TriggerBox (_session, data_type ()));
 		tb->set_owner (this);
 		add_processor (tb, _polarity);