add rbtree_node_t virtual destructor, possible memory leak
add rbtree_node_t virtual destructor, possible memory leak

dumubuchenglin/algorithms,shijiaxing/algorithms,xtaci/algorithms,qvex/algorithms,allengaller/algorithms,xtaci/algorithms,fengzhyuan/algorithms,ashwini0529/algorithms-1,xmfbit/algorithms,zhenglaizhang/algorithms,noname007/algorithms,tempbottle/algorithms,dumubuchenglin/algorithms,xmfbit/algorithms,greyg00s/algorithms,ee08b397/algorithms-1,ashwini0529/algorithms-1,jacklicn/algorithms,switchkiller/algorithms,shijiaxing/algorithms,switchkiller/algorithms,zhenglaizhang/algorithms,jacklicn/algorithms,fw1121/algorithms,sigma-random/algorithms,fw1121/algorithms,tempbottle/algorithms,allengaller/algorithms,ee08b397/algorithms-1,NoSmartNoMan/algorithms,hengwusanren/algorithms,noname007/algorithms,NoSmartNoMan/algorithms,M4573R/algorithms-1,hengwusanren/algorithms,greyg00s/algorithms,sigma-random/algorithms,fengzhyuan/algorithms,qvex/algorithms,lanbing510/Algorithms,M4573R/algorithms-1,lanbing510/Algorithms