Create mapping from nullifiers to received notes

This is used in the same way as CTxIn.prevout (e.g. to mark transactions dirty).

src/wallet/wallet.h

@@ -625,6 +625,7 @@ public:
         fBroadcastTransactions = false;
     }
 
+    std::map<uint256, JSOutPoint> mapNullifiers;
     std::map<uint256, CWalletTx> mapWallet;
 
     int64_t nOrderPosNext;
@@ -727,6 +728,7 @@ public:
     TxItems OrderedTxItems(std::list<CAccountingEntry>& acentries, std::string strAccount = "");
 
     void MarkDirty();
+    void UpdateNullifierNoteMap(const CWalletTx& wtx);
     bool AddToWallet(const CWalletTx& wtxIn, bool fFromLoadWallet, CWalletDB* pwalletdb);
     void SyncTransaction(const CTransaction& tx, const CBlock* pblock);
     bool AddToWalletIfInvolvingMe(const CTransaction& tx, const CBlock* pblock, bool fUpdate);