fix system drive selection under linux #17
fix system drive selection under linux #17

jinlmsft/Prajna,dVakulen/Prajna,MSRCCS/Prajna,leizhangcn/Prajna,BrunoBozza/Prajna,TonyAbell/Prajna,MSRCCS/Prajna,YuxiaoHu/Prajna,MSRCCS/Prajna,BrunoBozza/Prajna,cloudRoutine/Prajna,BrunoBozza/Prajna,dVakulen/Prajna,hongzhili/Prajna,jinlmsft/Prajna,jinlmsft/Prajna,YuxiaoHu/Prajna,hongzhili/Prajna,MSRCCS/Prajna,TonyAbell/Prajna,jinlmsft/Prajna,BrunoBozza/Prajna,cloudRoutine/Prajna,leizhangcn/Prajna