message: Erase mnListCache entry on UndoBlock
diff: @@ -328,9 +328,11 @@ bool CDeterministicMNManager::UndoBlock(const CBlock& block, const CBlockIndex*
  LOCK(cs);
  int nHeight = pindex->nHeight;
  + uint256 blockHash = block.GetHash();
  - evoDb.Erase(std::make_pair(DB_LIST_DIFF, block.GetHash()));
  - evoDb.Erase(std::make_pair(DB_LIST_SNAPSHOT, block.GetHash()));
  + evoDb.Erase(std::make_pair(DB_LIST_DIFF, blockHash));
  + evoDb.Erase(std::make_pair(DB_LIST_SNAPSHOT, blockHash));
  + mnListsCache.erase(blockHash);
  if (nHeight == GetSpork15Value()) {
  LogPrintf("CDeterministicMNManager::%s -- spork15 is not active anymore. nHeight=%d\n", __func__, nHeight);
  