message: Disallow copies of CChain
diff: @@ -519,6 +519,10 @@ private:
  std::vector<CBlockIndex*> vChain;
  public:
  + CChain() = default;
  + CChain(const CChain&) = delete;
  + CChain& operator=(const CChain&) = delete;
  +
  /** Returns the index entry for the genesis block of this chain, or nullptr if none. */
  CBlockIndex *Genesis() const {
  return vChain.size() > 0 ? vChain[0] : nullptr;
  