Improve .gitignore
Improve .gitignore

Copied good additions to .gitignore from https://github.com/dotnet/coreclr/

schellap/corert,schellap/corert,tijoytom/corert,gregkalapos/corert,yizhang82/corert,manu-silicon/corert,kyulee1/corert,mjp41/corert,sandreenko/corert,mjp41/corert,krytarowski/corert,krytarowski/corert,botaberg/corert,shrah/corert,shrah/corert,sandreenko/corert,sandreenko/corert,gregkalapos/corert,botaberg/corert,shrah/corert,tijoytom/corert,krytarowski/corert,gregkalapos/corert,gregkalapos/corert,mjp41/corert,tijoytom/corert,shrah/corert,manu-silicon/corert,tijoytom/corert,yizhang82/corert,kyulee1/corert,yizhang82/corert,mjp41/corert,botaberg/corert,schellap/corert,yizhang82/corert,mjp41/corert,schellap/corert,manu-silicon/corert,kyulee1/corert,schellap/corert,manu-silicon/corert,botaberg/corert,kyulee1/corert,sandreenko/corert,manu-silicon/corert,krytarowski/corert