message: Avoid unnecessary "Synchronizing blockheaders" log messages
diff: @@ -2561,7 +2561,7 @@ bool CChainState::ActivateBestChainStep(CValidationState& state, const CChainPar
  return true;
  }
  -static void NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
  +static bool NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
  bool fNotify = false;
  bool fInitialBlockDownload = false;
  static CBlockIndex* pindexHeaderOld = nullptr;
  @@ -2580,6 +2580,7 @@ static void NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
  if (fNotify) {
  uiInterface.NotifyHeaderTip(fInitialBlockDownload, pindexHeader);
  }
  + return fNotify;
  }
  static void LimitValidationInterfaceQueue() LOCKS_EXCLUDED(cs_main) {
  @@ -3400,8 +3401,7 @@ bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidatio
  }
  }
  }
  - NotifyHeaderTip();
  - {
  + if (NotifyHeaderTip()) {
  LOCK(cs_main);
  if (::ChainstateActive().IsInitialBlockDownload() && ppindex && *ppindex) {
  LogPrintf("Synchronizing blockheaders, height: %d (~%.2f%%)\n", (*ppindex)->nHeight, 100.0/((*ppindex)->nHeight+(GetAdjustedTime() - (*ppindex)->GetBlockTime()) / Params().GetConsensus().nPowTargetSpacing) * (*ppindex)->nHeight);
  