reader: simplify impl of IndexTableHelper::InsertCBEIndexSegment
reader: simplify impl of IndexTableHelper::InsertCBEIndexSegment

xunchangguo/BMX,kierank/bmxlib-bmx,xunchangguo/BMX,kierank/bmxlib-bmx,kierank/bmxlib-bmx,stuarthicks/bmx,xunchangguo/BMX,stuarthicks/bmx,stuarthicks/bmx,Limecraft/ebu-bmx,Limecraft/ebu-bmx,Limecraft/ebu-bmx