Fix RHEL.6 CI build (#24331)
Fix RHEL.6 CI build (#24331)

I have missed msbuild options separator in the build.sh
invocation when adding the /p:PortableBuild=false option.
ericstj/corefx,axelheer/corefx,axelheer/corefx,shimingsg/corefx,twsouthwick/corefx,ViktorHofer/corefx,mmitche/corefx,Ermiar/corefx,ravimeda/corefx,tijoytom/corefx,ViktorHofer/corefx,ViktorHofer/corefx,seanshpark/corefx,Ermiar/corefx,parjong/corefx,axelheer/corefx,wtgodbe/corefx,zhenlan/corefx,zhenlan/corefx,mmitche/corefx,wtgodbe/corefx,ptoonen/corefx,ptoonen/corefx,ravimeda/corefx,BrennanConroy/corefx,seanshpark/corefx,Ermiar/corefx,parjong/corefx,ericstj/corefx,Ermiar/corefx,ViktorHofer/corefx,fgreinacher/corefx,fgreinacher/corefx,Jiayili1/corefx,ravimeda/corefx,tijoytom/corefx,Jiayili1/corefx,zhenlan/corefx,BrennanConroy/corefx,Jiayili1/corefx,zhenlan/corefx,parjong/corefx,twsouthwick/corefx,twsouthwick/corefx,fgreinacher/corefx,zhenlan/corefx,Jiayili1/corefx,tijoytom/corefx,shimingsg/corefx,parjong/corefx,shimingsg/corefx,shimingsg/corefx,Ermiar/corefx,zhenlan/corefx,ericstj/corefx,seanshpark/corefx,mmitche/corefx,tijoytom/corefx,twsouthwick/corefx,wtgodbe/corefx,Jiayili1/corefx,Jiayili1/corefx,BrennanConroy/corefx,seanshpark/corefx,ptoonen/corefx,ravimeda/corefx,parjong/corefx,ViktorHofer/corefx,axelheer/corefx,Ermiar/corefx,twsouthwick/corefx,tijoytom/corefx,ravimeda/corefx,mmitche/corefx,ViktorHofer/corefx,ericstj/corefx,ptoonen/corefx,seanshpark/corefx,tijoytom/corefx,mmitche/corefx,zhenlan/corefx,wtgodbe/corefx,parjong/corefx,ericstj/corefx,ericstj/corefx,tijoytom/corefx,parjong/corefx,ravimeda/corefx,seanshpark/corefx,wtgodbe/corefx,mmitche/corefx,axelheer/corefx,twsouthwick/corefx,ptoonen/corefx,fgreinacher/corefx,Ermiar/corefx,ptoonen/corefx,mmitche/corefx,shimingsg/corefx,twsouthwick/corefx,ericstj/corefx,wtgodbe/corefx,ravimeda/corefx,seanshpark/corefx,shimingsg/corefx,wtgodbe/corefx,axelheer/corefx,shimingsg/corefx,ViktorHofer/corefx,ptoonen/corefx,Jiayili1/corefx