Revert the fix of the destructor of bwtree_index because of invalid read.
Revert the fix of the destructor of bwtree_index because of invalid read.

yingjunwu/peloton,PauloAmora/peloton,apavlo/peloton,malin1993ml/peloton,ShuxinLin/peloton,AngLi-Leon/peloton,phisiart/peloton-p3,wangziqi2016/peloton,vittvolt/15721-peloton,seojungmin/peloton,ShuxinLin/peloton,vittvolt/peloton,wangziqi2016/peloton,eric-haibin-lin/peloton-1,AllisonWang/peloton,seojungmin/peloton,ShuxinLin/peloton,jessesleeping/iso_peloton,eric-haibin-lin/peloton-1,AngLi-Leon/peloton,vittvolt/15721-peloton,vittvolt/peloton,seojungmin/peloton,PauloAmora/peloton,apavlo/peloton,jessesleeping/iso_peloton,vittvolt/15721-peloton,jessesleeping/iso_peloton,phisiart/peloton-p3,apavlo/peloton,ShuxinLin/peloton,yingjunwu/peloton,vittvolt/peloton,PauloAmora/peloton,prashasthip/peloton,prashasthip/peloton,apavlo/peloton,AngLi-Leon/peloton,AllisonWang/peloton,wangziqi2016/peloton,haojin2/peloton,wangziqi2016/peloton,AllisonWang/peloton,AllisonWang/peloton,malin1993ml/peloton,jessesleeping/iso_peloton,prashasthip/peloton,vittvolt/15721-peloton,ShuxinLin/peloton,phisiart/peloton-p3,seojungmin/peloton,yingjunwu/peloton,AllisonWang/peloton,vittvolt/15721-peloton,yingjunwu/peloton,AngLi-Leon/peloton,haojin2/peloton,jessesleeping/iso_peloton,haojin2/peloton,eric-haibin-lin/peloton-1,phisiart/peloton-p3,PauloAmora/peloton,yingjunwu/peloton,AngLi-Leon/peloton,prashasthip/peloton,malin1993ml/peloton,cmu-db/peloton,vittvolt/peloton,jessesleeping/iso_peloton,wangziqi2016/peloton,haojin2/peloton,haojin2/peloton,seojungmin/peloton,prashasthip/peloton,malin1993ml/peloton,eric-haibin-lin/peloton-1,cmu-db/peloton,eric-haibin-lin/peloton-1,apavlo/peloton,ShuxinLin/peloton,apavlo/peloton,eric-haibin-lin/peloton-1,cmu-db/peloton,PauloAmora/peloton,cmu-db/peloton,PauloAmora/peloton,AllisonWang/peloton,phisiart/peloton-p3,prashasthip/peloton,AngLi-Leon/peloton,malin1993ml/peloton,haojin2/peloton,cmu-db/peloton,vittvolt/peloton,phisiart/peloton-p3,vittvolt/15721-peloton,wangziqi2016/peloton,seojungmin/peloton,cmu-db/peloton,yingjunwu/peloton,jessesleeping/iso_peloton,malin1993ml/peloton,vittvolt/peloton