Set missed default value for coreclr runtest.cmd.
Set missed default value for coreclr runtest.cmd.

__MSBuildBuildArch is set to x64 by default like __BuildArch. Fix 7488.

krk/coreclr,dpodder/coreclr,mskvortsov/coreclr,sjsinju/coreclr,cmckinsey/coreclr,AlexGhiondea/coreclr,pgavlin/coreclr,hseok-oh/coreclr,krytarowski/coreclr,neurospeech/coreclr,JosephTremoulet/coreclr,kyulee1/coreclr,cshung/coreclr,botaberg/coreclr,kyulee1/coreclr,yeaicc/coreclr,cshung/coreclr,James-Ko/coreclr,JosephTremoulet/coreclr,parjong/coreclr,alexperovich/coreclr,hseok-oh/coreclr,ramarag/coreclr,hseok-oh/coreclr,James-Ko/coreclr,YongseopKim/coreclr,qiudesong/coreclr,tijoytom/coreclr,JonHanna/coreclr,AlexGhiondea/coreclr,jamesqo/coreclr,parjong/coreclr,poizan42/coreclr,poizan42/coreclr,yizhang82/coreclr,sagood/coreclr,jamesqo/coreclr,wateret/coreclr,rartemev/coreclr,russellhadley/coreclr,yeaicc/coreclr,dpodder/coreclr,ruben-ayrapetyan/coreclr,hseok-oh/coreclr,neurospeech/coreclr,jamesqo/coreclr,cydhaselton/coreclr,neurospeech/coreclr,Dmitry-Me/coreclr,neurospeech/coreclr,yeaicc/coreclr,wateret/coreclr,krytarowski/coreclr,gkhanna79/coreclr,dpodder/coreclr,yeaicc/coreclr,poizan42/coreclr,parjong/coreclr,dpodder/coreclr,krytarowski/coreclr,pgavlin/coreclr,ragmani/coreclr,hseok-oh/coreclr,YongseopKim/coreclr,dasMulli/coreclr,ramarag/coreclr,Dmitry-Me/coreclr,AlexGhiondea/coreclr,yeaicc/coreclr,ruben-ayrapetyan/coreclr,tijoytom/coreclr,russellhadley/coreclr,James-Ko/coreclr,tijoytom/coreclr,botaberg/coreclr,cshung/coreclr,JosephTremoulet/coreclr,krk/coreclr,krytarowski/coreclr,krytarowski/coreclr,cydhaselton/coreclr,wtgodbe/coreclr,russellhadley/coreclr,kyulee1/coreclr,russellhadley/coreclr,yizhang82/coreclr,yeaicc/coreclr,cshung/coreclr,poizan42/coreclr,sjsinju/coreclr,gkhanna79/coreclr,pgavlin/coreclr,kyulee1/coreclr,russellhadley/coreclr,yizhang82/coreclr,ragmani/coreclr,sagood/coreclr,gkhanna79/coreclr,cshung/coreclr,dpodder/coreclr,Dmitry-Me/coreclr,James-Ko/coreclr,JonHanna/coreclr,mskvortsov/coreclr,YongseopKim/coreclr,krk/coreclr,yizhang82/coreclr,sagood/coreclr,dpodder/coreclr,mskvortsov/coreclr,JosephTremoulet/coreclr,mmitche/coreclr,Dmitry-Me/coreclr,ruben-ayrapetyan/coreclr,mskvortsov/coreclr,mmitche/coreclr,krytarowski/coreclr,cydhaselton/coreclr,AlexGhiondea/coreclr,mskvortsov/coreclr,dasMulli/coreclr,alexperovich/coreclr,sagood/coreclr,neurospeech/coreclr,botaberg/coreclr,tijoytom/coreclr,dasMulli/coreclr,wtgodbe/coreclr,alexperovich/coreclr,gkhanna79/coreclr,Dmitry-Me/coreclr,krk/coreclr,ramarag/coreclr,tijoytom/coreclr,wateret/coreclr,YongseopKim/coreclr,qiudesong/coreclr,gkhanna79/coreclr,alexperovich/coreclr,parjong/coreclr,sjsinju/coreclr,kyulee1/coreclr,JonHanna/coreclr,ramarag/coreclr,sagood/coreclr,cmckinsey/coreclr,jamesqo/coreclr,hseok-oh/coreclr,cydhaselton/coreclr,mskvortsov/coreclr,yizhang82/coreclr,jamesqo/coreclr,russellhadley/coreclr,rartemev/coreclr,dasMulli/coreclr,ruben-ayrapetyan/coreclr,neurospeech/coreclr,ragmani/coreclr,gkhanna79/coreclr,YongseopKim/coreclr,botaberg/coreclr,yizhang82/coreclr,rartemev/coreclr,cmckinsey/coreclr,jamesqo/coreclr,JosephTremoulet/coreclr,sjsinju/coreclr,cmckinsey/coreclr,botaberg/coreclr,alexperovich/coreclr,pgavlin/coreclr,Dmitry-Me/coreclr,ramarag/coreclr,JosephTremoulet/coreclr,kyulee1/coreclr,James-Ko/coreclr,mmitche/coreclr,ragmani/coreclr,rartemev/coreclr,wateret/coreclr,JonHanna/coreclr,cshung/coreclr,ruben-ayrapetyan/coreclr,pgavlin/coreclr,JonHanna/coreclr,AlexGhiondea/coreclr,krk/coreclr,mmitche/coreclr,qiudesong/coreclr,tijoytom/coreclr,poizan42/coreclr,botaberg/coreclr,ragmani/coreclr,Dmitry-Me/coreclr,wtgodbe/coreclr,wtgodbe/coreclr,parjong/coreclr,cmckinsey/coreclr,ramarag/coreclr,qiudesong/coreclr,qiudesong/coreclr,James-Ko/coreclr,AlexGhiondea/coreclr,dasMulli/coreclr,rartemev/coreclr,mmitche/coreclr,wtgodbe/coreclr,cydhaselton/coreclr,cydhaselton/coreclr,dasMulli/coreclr,qiudesong/coreclr,parjong/coreclr,sjsinju/coreclr,wateret/coreclr,ruben-ayrapetyan/coreclr,mmitche/coreclr,cmckinsey/coreclr,poizan42/coreclr,rartemev/coreclr,YongseopKim/coreclr,wateret/coreclr,ramarag/coreclr,dasMulli/coreclr,ragmani/coreclr,pgavlin/coreclr,sjsinju/coreclr,yeaicc/coreclr,krk/coreclr,JonHanna/coreclr,cmckinsey/coreclr,alexperovich/coreclr,wtgodbe/coreclr,sagood/coreclr