message: Add additional lock on zerocoinspend.
diff: @@ -4614,7 +4614,7 @@ void CWallet::AutoZeromint()
  CCoinControl coinControl;
  CAmount nBalance = GetMintableBalance(vOutputs); // won't consider locked outputs or basecoin address
  - if (nBalance < 10){
  + if (nBalance <= libzerocoin::ZerocoinDenominationToAmount(libzerocoin::CoinDenomination::ZQ_TEN)){
  LogPrint(BCLog::SELECTCOINS, "CWallet::AutoZeromint(): available balance (%ld) too small for minting zPIV\n", nBalance);
  return;
  }
  @@ -5551,6 +5551,7 @@ bool CWallet::SpendZerocoin(CAmount nValue, int nSecurityLevel, CZerocoinSpendRe
  }
  CValidationState state;
  + LOCK(cs_main);
  if (!AcceptToMemoryPool(mempool, state, wtxCurrent.tx, nullptr /* pfMissingInputs */, nullptr /* plTxnReplaced */,
  false /* bypass_limits */, maxTxFee, true)) {
  // failed mempool validation for one of the transactions so no partial transaction is being committed
  