Fix use-after-free which may happen during shutdown

If a module, e.g. keepnick, tries to remove a timer in
OnIRCDisconnected.

Thanks to KindOne for the report.

modules/keepnick.cpp

@@ -121,7 +121,7 @@ public:
 			return;
 
 		m_pTimer->Stop();
-		RemTimer(m_pTimer->GetName());
+		RemTimer(m_pTimer);
 		m_pTimer = NULL;
 	}