message: Use compare_exchange_weak when setting bestBlockHeight
diff: @@ -66,8 +66,12 @@ bool ModalOverlay::event(QEvent* ev) {
  void ModalOverlay::setKnownBestHeight(int count, const QDateTime& blockDate)
  {
  - if (count > bestBlockHeight.load())
  - bestBlockHeight.store(count);
  + int nHeight = bestBlockHeight.load();
  + if (count > nHeight)
  + {
  + bestBlockHeight.compare_exchange_weak(nHeight, count);
  + nHeight = bestBlockHeight.load();
  + }
  }
  void ModalOverlay::tipUpdate(int count, const QDateTime& blockDate, double nVerificationProgress)
  