message: Fix for v2 mint/spend
diff: @@ -2714,6 +2714,8 @@ UniValue mintzerocoin(const UniValue& params, bool fHelp)
  }
  zerocoinTx.randomness = newCoin.getRandomness();
  zerocoinTx.serialNumber = newCoin.getSerialNumber();
  + const unsigned char *ecdsaSecretKey = newCoin.getEcdsaSeckey();
  + zerocoinTx.ecdsaSecretKey = std::vector<unsigned char>(ecdsaSecretKey, ecdsaSecretKey+32);
  walletdb.WriteZerocoinEntry(zerocoinTx);
  return pubCoin.getValue().GetHex();
  