events: Output the event that is leaking

Signed-off-by: Fedor Indutny <fedor@indutny.com>

lib/events.js

@@ -173,9 +173,9 @@ EventEmitter.prototype.addListener = function addListener(type, listener) {
     if (m && m > 0 && this._events[type].length > m) {
       this._events[type].warned = true;
       console.error('(node) warning: possible EventEmitter memory ' +
-                    'leak detected. %d listeners added. ' +
+                    'leak detected. %d %s listeners added. ' +
                     'Use emitter.setMaxListeners() to increase limit.',
-                    this._events[type].length);
+                    this._events[type].length, type);
       console.trace();
     }
   }