render: further simplified job times

Outside of silly mistakes, this should be significantly faster and more stable.

app/threading/threadticket.cpp

@@ -27,7 +27,6 @@ RenderTicket::RenderTicket() :
   has_result_(false),
   finish_count_(0)
 {
-  SetJobTime();
 }
 
 void RenderTicket::WaitForFinished(QMutex *mutex)

app/threading/threadticket.h

@@ -38,16 +38,6 @@ class RenderTicket : public QObject
 public:
   RenderTicket();
 
-  JobTime GetJobTime() const
-  {
-    return job_time_;
-  }
-
-  void SetJobTime()
-  {
-    job_time_.Acquire();
-  }
-
   /**
    * @brief Get the ticket's current state
    *
@@ -137,8 +127,6 @@ private:
 
   QWaitCondition wait_;
 
-  JobTime job_time_;
-
 };
 
 using RenderTicketPtr = std::shared_ptr<RenderTicket>;