message: Default m_TimeUnit to invalid so that UpdateDurationColumn runs 1st time
diff: @@ -119,7 +119,7 @@ private:
  void ExportDrawcall(QTextStream &writer, int maxNameLength, int indent, bool firstchild,
  const DrawcallDescription &drawcall);
  - TimeUnit m_TimeUnit = TimeUnit::Microseconds;
  + TimeUnit m_TimeUnit = TimeUnit::Count;
  rdctype::array<CounterResult> m_Times;
  