Enable RHEL6 and CentOS 6 RID detection in build (#13101)
Enable RHEL6 and CentOS 6 RID detection in build (#13101)

This change adds RHEL6 and CentOS 6 RID detection to build.sh.
These distros don't have the /etc/os-release file and so
we need to use another source - the /etc/redhat-release file
ruben-ayrapetyan/coreclr,russellhadley/coreclr,wateret/coreclr,ragmani/coreclr,dpodder/coreclr,AlexGhiondea/coreclr,tijoytom/coreclr,parjong/coreclr,gkhanna79/coreclr,mmitche/coreclr,russellhadley/coreclr,rartemev/coreclr,wateret/coreclr,AlexGhiondea/coreclr,rartemev/coreclr,parjong/coreclr,hseok-oh/coreclr,yizhang82/coreclr,rartemev/coreclr,krk/coreclr,mskvortsov/coreclr,tijoytom/coreclr,yizhang82/coreclr,tijoytom/coreclr,ragmani/coreclr,ragmani/coreclr,cshung/coreclr,dpodder/coreclr,wateret/coreclr,cshung/coreclr,mmitche/coreclr,botaberg/coreclr,wtgodbe/coreclr,hseok-oh/coreclr,JonHanna/coreclr,krk/coreclr,yizhang82/coreclr,JosephTremoulet/coreclr,cshung/coreclr,botaberg/coreclr,tijoytom/coreclr,poizan42/coreclr,mmitche/coreclr,JosephTremoulet/coreclr,parjong/coreclr,mskvortsov/coreclr,mmitche/coreclr,cydhaselton/coreclr,mskvortsov/coreclr,ruben-ayrapetyan/coreclr,ragmani/coreclr,wtgodbe/coreclr,AlexGhiondea/coreclr,mskvortsov/coreclr,ragmani/coreclr,hseok-oh/coreclr,AlexGhiondea/coreclr,russellhadley/coreclr,poizan42/coreclr,yizhang82/coreclr,cshung/coreclr,botaberg/coreclr,gkhanna79/coreclr,kyulee1/coreclr,JosephTremoulet/coreclr,tijoytom/coreclr,krk/coreclr,JosephTremoulet/coreclr,rartemev/coreclr,parjong/coreclr,wtgodbe/coreclr,parjong/coreclr,kyulee1/coreclr,JonHanna/coreclr,ruben-ayrapetyan/coreclr,AlexGhiondea/coreclr,poizan42/coreclr,dpodder/coreclr,cshung/coreclr,kyulee1/coreclr,parjong/coreclr,cshung/coreclr,hseok-oh/coreclr,krk/coreclr,mskvortsov/coreclr,cydhaselton/coreclr,cydhaselton/coreclr,yizhang82/coreclr,JonHanna/coreclr,JonHanna/coreclr,wateret/coreclr,wateret/coreclr,JosephTremoulet/coreclr,gkhanna79/coreclr,JosephTremoulet/coreclr,rartemev/coreclr,JonHanna/coreclr,hseok-oh/coreclr,dpodder/coreclr,ruben-ayrapetyan/coreclr,russellhadley/coreclr,gkhanna79/coreclr,gkhanna79/coreclr,kyulee1/coreclr,hseok-oh/coreclr,JonHanna/coreclr,gkhanna79/coreclr,botaberg/coreclr,kyulee1/coreclr,russellhadley/coreclr,botaberg/coreclr,poizan42/coreclr,cydhaselton/coreclr,ragmani/coreclr,mskvortsov/coreclr,poizan42/coreclr,tijoytom/coreclr,cydhaselton/coreclr,wtgodbe/coreclr,dpodder/coreclr,AlexGhiondea/coreclr,krk/coreclr,yizhang82/coreclr,wtgodbe/coreclr,wateret/coreclr,russellhadley/coreclr,dpodder/coreclr,ruben-ayrapetyan/coreclr,kyulee1/coreclr,botaberg/coreclr,poizan42/coreclr,wtgodbe/coreclr,krk/coreclr,mmitche/coreclr,cydhaselton/coreclr,rartemev/coreclr,mmitche/coreclr,ruben-ayrapetyan/coreclr