fixed a leak in btree
fixed a leak in btree

zhenglaizhang/algorithms,NoSmartNoMan/algorithms,lanbing510/Algorithms,jacklicn/algorithms,fw1121/algorithms,dumubuchenglin/algorithms,ashwini0529/algorithms-1,allengaller/algorithms,switchkiller/algorithms,tempbottle/algorithms,hengwusanren/algorithms,xtaci/algorithms,jacklicn/algorithms,switchkiller/algorithms,hengwusanren/algorithms,greyg00s/algorithms,xmfbit/algorithms,noname007/algorithms,xtaci/algorithms,xmfbit/algorithms,M4573R/algorithms-1,fengzhyuan/algorithms,zhenglaizhang/algorithms,fw1121/algorithms,shijiaxing/algorithms,greyg00s/algorithms,lanbing510/Algorithms,qvex/algorithms,shijiaxing/algorithms,sigma-random/algorithms,M4573R/algorithms-1,sigma-random/algorithms,allengaller/algorithms,tempbottle/algorithms,qvex/algorithms,NoSmartNoMan/algorithms,dumubuchenglin/algorithms,ashwini0529/algorithms-1,fengzhyuan/algorithms,noname007/algorithms