iterator: IndexedIterator: Fixes data iterator that may not get released
iterator: IndexedIterator: Fixes data iterator that may not get released

conseweb/goleveldb,trigrass2/goleveldb,chai2010/goleveldb,rentongzhang/goleveldb,hustbill/goleveldb,ngaut/goleveldb,syndtr/goleveldb,btcsuite/goleveldb,FactomProject/goleveldb,zzl0/goleveldb,no2key/goleveldb