Fail init-tools atomically
Fail init-tools atomically

Before this change, a failure fairly early in the `init-tools.sh` process could result in subsequent attempts being short-circuited.

This introduces a marker file that is only written at the very end of the script, so that a `dotnet restore` or `init-tools.sh`-from-package failure can be retried immediately.
axelheer/corefx,iamjasonp/corefx,jhendrixMSFT/corefx,billwert/corefx,nbarbettini/corefx,Jiayili1/corefx,richlander/corefx,mmitche/corefx,weltkante/corefx,Ermiar/corefx,manu-silicon/corefx,alexperovich/corefx,rjxby/corefx,zhenlan/corefx,dotnet-bot/corefx,parjong/corefx,weltkante/corefx,ptoonen/corefx,zhenlan/corefx,cydhaselton/corefx,JosephTremoulet/corefx,ravimeda/corefx,ViktorHofer/corefx,JosephTremoulet/corefx,shmao/corefx,mazong1123/corefx,ravimeda/corefx,marksmeltzer/corefx,yizhang82/corefx,elijah6/corefx,krytarowski/corefx,tijoytom/corefx,JosephTremoulet/corefx,shmao/corefx,ViktorHofer/corefx,ericstj/corefx,richlander/corefx,shmao/corefx,billwert/corefx,zhenlan/corefx,lggomez/corefx,MaggieTsang/corefx,twsouthwick/corefx,alphonsekurian/corefx,zhenlan/corefx,jlin177/corefx,mmitche/corefx,iamjasonp/corefx,zhenlan/corefx,gkhanna79/corefx,twsouthwick/corefx,wtgodbe/corefx,lggomez/corefx,jlin177/corefx,dotnet-bot/corefx,Petermarcu/corefx,ptoonen/corefx,Petermarcu/corefx,mazong1123/corefx,axelheer/corefx,jlin177/corefx,weltkante/corefx,krk/corefx,billwert/corefx,alphonsekurian/corefx,shimingsg/corefx,mmitche/corefx,rjxby/corefx,jhendrixMSFT/corefx,lggomez/corefx,rahku/corefx,marksmeltzer/corefx,alphonsekurian/corefx,alexperovich/corefx,manu-silicon/corefx,Ermiar/corefx,the-dwyer/corefx,ViktorHofer/corefx,Petermarcu/corefx,tijoytom/corefx,ptoonen/corefx,cydhaselton/corefx,alexperovich/corefx,Jiayili1/corefx,iamjasonp/corefx,cydhaselton/corefx,dotnet-bot/corefx,elijah6/corefx,nchikanov/corefx,seanshpark/corefx,ravimeda/corefx,Ermiar/corefx,stone-li/corefx,twsouthwick/corefx,lggomez/corefx,zhenlan/corefx,nchikanov/corefx,nchikanov/corefx,axelheer/corefx,BrennanConroy/corefx,shimingsg/corefx,dotnet-bot/corefx,wtgodbe/corefx,Jiayili1/corefx,BrennanConroy/corefx,MaggieTsang/corefx,seanshpark/corefx,rjxby/corefx,weltkante/corefx,stephenmichaelf/corefx,axelheer/corefx,iamjasonp/corefx,tijoytom/corefx,the-dwyer/corefx,yizhang82/corefx,parjong/corefx,twsouthwick/corefx,Petermarcu/corefx,twsouthwick/corefx,nchikanov/corefx,fgreinacher/corefx,mmitche/corefx,Ermiar/corefx,stone-li/corefx,jhendrixMSFT/corefx,lggomez/corefx,parjong/corefx,mazong1123/corefx,dhoehna/corefx,gkhanna79/corefx,stone-li/corefx,ericstj/corefx,fgreinacher/corefx,jhendrixMSFT/corefx,alexperovich/corefx,rjxby/corefx,shmao/corefx,shmao/corefx,nbarbettini/corefx,dhoehna/corefx,elijah6/corefx,stephenmichaelf/corefx,nchikanov/corefx,krytarowski/corefx,the-dwyer/corefx,jhendrixMSFT/corefx,YoupHulsebos/corefx,DnlHarvey/corefx,dhoehna/corefx,iamjasonp/corefx,manu-silicon/corefx,nbarbettini/corefx,ericstj/corefx,rahku/corefx,nbarbettini/corefx,stone-li/corefx,elijah6/corefx,yizhang82/corefx,weltkante/corefx,the-dwyer/corefx,iamjasonp/corefx,wtgodbe/corefx,alphonsekurian/corefx,rjxby/corefx,rubo/corefx,Petermarcu/corefx,shimingsg/corefx,stone-li/corefx,YoupHulsebos/corefx,manu-silicon/corefx,tijoytom/corefx,Ermiar/corefx,MaggieTsang/corefx,elijah6/corefx,krk/corefx,ericstj/corefx,alexperovich/corefx,krk/corefx,the-dwyer/corefx,billwert/corefx,parjong/corefx,lggomez/corefx,shimingsg/corefx,ravimeda/corefx,gkhanna79/corefx,richlander/corefx,cydhaselton/corefx,Jiayili1/corefx,nbarbettini/corefx,ViktorHofer/corefx,alphonsekurian/corefx,seanshpark/corefx,JosephTremoulet/corefx,elijah6/corefx,MaggieTsang/corefx,weltkante/corefx,shimingsg/corefx,jlin177/corefx,twsouthwick/corefx,krk/corefx,richlander/corefx,marksmeltzer/corefx,rahku/corefx,billwert/corefx,rubo/corefx,wtgodbe/corefx,DnlHarvey/corefx,stephenmichaelf/corefx,MaggieTsang/corefx,yizhang82/corefx,DnlHarvey/corefx,the-dwyer/corefx,ptoonen/corefx,stone-li/corefx,jlin177/corefx,krk/corefx,alexperovich/corefx,parjong/corefx,lggomez/corefx,mazong1123/corefx,manu-silicon/corefx,fgreinacher/corefx,stephenmichaelf/corefx,wtgodbe/corefx,nbarbettini/corefx,Ermiar/corefx,stephenmichaelf/corefx,tijoytom/corefx,parjong/corefx,DnlHarvey/corefx,seanshpark/corefx,ravimeda/corefx,rubo/corefx,shmao/corefx,jlin177/corefx,cydhaselton/corefx,iamjasonp/corefx,yizhang82/corefx,rahku/corefx,mazong1123/corefx,yizhang82/corefx,krytarowski/corefx,jlin177/corefx,manu-silicon/corefx,dhoehna/corefx,Petermarcu/corefx,rahku/corefx,richlander/corefx,ViktorHofer/corefx,shmao/corefx,mmitche/corefx,MaggieTsang/corefx,krytarowski/corefx,jhendrixMSFT/corefx,dhoehna/corefx,alphonsekurian/corefx,yizhang82/corefx,manu-silicon/corefx,ptoonen/corefx,gkhanna79/corefx,parjong/corefx,JosephTremoulet/corefx,ericstj/corefx,YoupHulsebos/corefx,seanshpark/corefx,nchikanov/corefx,stephenmichaelf/corefx,richlander/corefx,krk/corefx,YoupHulsebos/corefx,gkhanna79/corefx,tijoytom/corefx,elijah6/corefx,marksmeltzer/corefx,nchikanov/corefx,krytarowski/corefx,ptoonen/corefx,Jiayili1/corefx,mazong1123/corefx,alphonsekurian/corefx,nbarbettini/corefx,dhoehna/corefx,axelheer/corefx,shimingsg/corefx,billwert/corefx,shimingsg/corefx,marksmeltzer/corefx,marksmeltzer/corefx,ptoonen/corefx,fgreinacher/corefx,jhendrixMSFT/corefx,ravimeda/corefx,Ermiar/corefx,seanshpark/corefx,rahku/corefx,ViktorHofer/corefx,rubo/corefx,stephenmichaelf/corefx,zhenlan/corefx,axelheer/corefx,marksmeltzer/corefx,krytarowski/corefx,Jiayili1/corefx,dotnet-bot/corefx,ericstj/corefx,dotnet-bot/corefx,DnlHarvey/corefx,ravimeda/corefx,mazong1123/corefx,billwert/corefx,weltkante/corefx,ViktorHofer/corefx,JosephTremoulet/corefx,stone-li/corefx,mmitche/corefx,MaggieTsang/corefx,wtgodbe/corefx,ericstj/corefx,tijoytom/corefx,rjxby/corefx,DnlHarvey/corefx,rubo/corefx,Jiayili1/corefx,DnlHarvey/corefx,cydhaselton/corefx,YoupHulsebos/corefx,alexperovich/corefx,Petermarcu/corefx,krytarowski/corefx,the-dwyer/corefx,richlander/corefx,JosephTremoulet/corefx,rahku/corefx,rjxby/corefx,dotnet-bot/corefx,twsouthwick/corefx,gkhanna79/corefx,YoupHulsebos/corefx,BrennanConroy/corefx,cydhaselton/corefx,mmitche/corefx,gkhanna79/corefx,wtgodbe/corefx,YoupHulsebos/corefx,seanshpark/corefx,dhoehna/corefx,krk/corefx