message: Performance Regression Fix: Pre-Allocate txChanged vector
  coming from btc@ec81881b86b9680fcdcc42fd3ba31f04b8d09714
diff: @@ -2780,7 +2780,7 @@ bool static ConnectTip(CValidationState& state, CBlockIndex* pindexNew, const CB
  UpdateTip(pindexNew);
  for(unsigned int i=0; i < pblock->vtx.size(); i++) {
  - txChanged.push_back(std::make_tuple(pblock->vtx[i], pindexNew, i));
  + txChanged.emplace_back(pblock->vtx[i], pindexNew, i);
  }
  int64_t nTime6 = GetTimeMicros();
  @@ -3001,12 +3001,15 @@ bool ActivateBestChain(CValidationState& state, const CBlock* pblock, bool fAlre
  CBlockIndex* pindexNewTip = nullptr;
  CBlockIndex* pindexMostWork = nullptr;
  + std::vector<std::tuple<CTransaction,CBlockIndex*,int>> txChanged;
  + if (pblock)
  + txChanged.reserve(pblock->vtx.size());
  do {
  + txChanged.clear();
  boost::this_thread::interruption_point();
  const CBlockIndex *pindexFork;
  std::list<CTransaction> txConflicted;
  - std::vector<std::tuple<CTransaction,CBlockIndex*,int>> txChanged;
  bool fInitialDownload;
  while (true) {
  TRY_LOCK(cs_main, lockMain);
  