Clear vTxHashes when mapTx is cleared

Author: Bushstar

src/txmempool.cpp

@@ -704,6 +704,7 @@ void CTxMemPool::removeForBlock(const std::vector<CTransactionRef>& vtx, unsigne
 
 void CTxMemPool::_clear()
 {
+    vTxHashes.clear();
     mapTx.clear();
     mapNextTx.clear();
     totalTxSize = 0;