JobQueue: fixed incorrect requeuing.

* A dependent job was requeued even if it wasn't part of the queue
  before. The code relied on dependent jobs being already enqueued;
  but that cannot be guaranteed.
* If a job failed, its dependent jobs are now also set to failed, so
  that they won't be requeued at a later point.
* This caused some of the "Launching xxx failed: Operation not allowed"
  messages in the boot process. Those actually weren't harmless, and
  could mess up the natural job order.

headers/private/support/JobPrivate.h

@@ -30,6 +30,16 @@ public:
 		fJob._ClearTicketNumber();
 	}
 
+	void SetState(BJobState state)
+	{
+		fJob.SetState(state);
+	}
+
+	void NotifyStateListeners()
+	{
+		fJob.NotifyStateListeners();
+	}
+
 private:
 			BJob&				fJob;
 };