Track coinbase spends in CTxMemPoolEntry

This allows us to optimize CTxMemPool::removeForReorg.

src/txmempool.h

@@ -67,6 +67,7 @@ private:
     unsigned int entryHeight; //! Chain height when entering the mempool
     bool hadNoDependencies; //! Not dependent on any other txs when it entered the mempool
     CAmount inChainInputValue; //! Sum of all txin values that are already in blockchain
+    bool spendsCoinbase; //! keep track of transactions that spend a coinbase
 
     // Information about descendants of this transaction that are in the
     // mempool; if we remove this transaction we must remove all of these
@@ -80,7 +81,7 @@ private:
 public:
     CTxMemPoolEntry(const CTransaction& _tx, const CAmount& _nFee,
                     int64_t _nTime, double _entryPriority, unsigned int _entryHeight,
-                    bool poolHasNoInputsOf, CAmount _inChainInputValue);
+                    bool poolHasNoInputsOf, CAmount _inChainInputValue, bool spendsCoinbase);
     CTxMemPoolEntry(const CTxMemPoolEntry& other);
 
     const CTransaction& GetTx() const { return this->tx; }
@@ -109,6 +110,8 @@ public:
     uint64_t GetCountWithDescendants() const { return nCountWithDescendants; }
     uint64_t GetSizeWithDescendants() const { return nSizeWithDescendants; }
     CAmount GetFeesWithDescendants() const { return nFeesWithDescendants; }
+
+    bool GetSpendsCoinbase() const { return spendsCoinbase; }
 };
 
 // Helpers for modifying CTxMemPool::mapTx, which is a boost multi_index.