message: [RPC] Disable zerocoin minting
  disabling also remint of change of a zc spend
diff: @@ -2769,6 +2769,8 @@ UniValue mintzerocoin(const UniValue& params, bool fHelp)
  "\nAs a json rpc call\n" +
  HelpExampleRpc("mintzerocoin", "13, \"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":1}]\""));
  + throw JSONRPCError(RPC_WALLET_ERROR, "zPIV minting is DISABLED");
  + /*
  LOCK2(cs_main, pwalletMain->cs_wallet);
  if (params.size() == 1)
  @@ -2837,6 +2839,7 @@ UniValue mintzerocoin(const UniValue& params, bool fHelp)
  }
  return arrMints;
  + */
  }
  UniValue spendzerocoin(const UniValue& params, bool fHelp)
  @@ -2891,6 +2894,8 @@ UniValue spendzerocoin(const UniValue& params, bool fHelp)
  CAmount nAmount = AmountFromValue(params[0]); // Spending amount
  bool fMintChange = params[1].get_bool(); // Mint change to zPIV
  + if (fMintChange)
  + throw JSONRPCError(RPC_WALLET_ERROR, "zPIV minting is DISABLED, cannot mint change");
  bool fMinimizeChange = params[2].get_bool(); // Minimize change
  std::string address_str = params.size() > 3 ? params[3].get_str() : "";
  bool ispublicspend = params.size() > 4 ? params[3].get_bool() : true;
  @@ -3001,6 +3006,10 @@ UniValue spendzerocoinmints(const UniValue& params, bool fHelp)
  extern UniValue DoZpivSpend(const CAmount nAmount, bool fMintChange, bool fMinimizeChange, vector<CZerocoinMint>& vMintsSelected, std::string address_str, bool ispublicspend)
  {
  + // zerocoin MINT is disabled. fMintChange should be false here. Double check
  + if (fMintChange)
  + throw JSONRPCError(RPC_WALLET_ERROR, "zPIV minting is DISABLED, cannot mint change");
  +
  int64_t nTimeStart = GetTimeMillis();
  CBitcoinAddress address = CBitcoinAddress(); // Optional sending address. Dummy initialization here.
  CWalletTx wtx;
  