cache: use render job times to synchronize cache

Ensure old inaccurate jobs are never prioritized over current jobs.

app/render/playbackcache.h

@@ -80,14 +80,14 @@ signals:
   void LengthChanged(const OLIVE_NAMESPACE::rational& r);
 
 protected:
-  void Validate(const TimeRange& r);
-
   void NoLockInvalidate(const TimeRange& r);
 
   void NoLockValidate(const TimeRange& r);
 
   void NoLockSetLength(const rational& r);
 
+  bool JobIsCurrent(const TimeRange& r, qint64 job_time);
+
   const rational& NoLockGetLength() const
   {
     return length_;
@@ -110,10 +110,19 @@ protected:
   }
 
 private:
+  void RemoveRangeFromJobs(const TimeRange& remove);
+
   QMutex lock_;
 
   TimeRangeList invalidated_;
 
+  struct JobIdentifier {
+    TimeRange range;
+    qint64 job_time;
+  };
+
+  QList<JobIdentifier> jobs_;
+
   rational length_;
 
 };