Added libunwind in travis file
Added libunwind in travis file

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