message: [MN] Small refactor to the `mapMasternodesLastVote` map.
diff: @@ -235,7 +235,7 @@ private:
  public:
  std::map<uint256, CMasternodePaymentWinner> mapMasternodePayeeVotes;
  std::map<int, CMasternodeBlockPayees> mapMasternodeBlocks;
  - std::map<uint256, int> mapMasternodesLastVote; //prevout.hash + prevout.n, nBlockHeight
  + std::map<COutPoint, int> mapMasternodesLastVote; //prevout, nBlockHeight
  CMasternodePayments()
  {
  @@ -265,14 +265,14 @@ public:
  {
  LOCK(cs_mapMasternodePayeeVotes);
  - if (mapMasternodesLastVote.count(outMasternode.hash + outMasternode.n)) {
  - if (mapMasternodesLastVote[outMasternode.hash + outMasternode.n] == nBlockHeight) {
  + if (mapMasternodesLastVote.count(outMasternode)) {
  + if (mapMasternodesLastVote[outMasternode] == nBlockHeight) {
  return false;
  }
  }
  //record this masternode voted
  - mapMasternodesLastVote[outMasternode.hash + outMasternode.n] = nBlockHeight;
  + mapMasternodesLastVote[outMasternode] = nBlockHeight;
  return true;
  }
  