Treat RHEL 7.x versions as RHEL 7 when building
Treat RHEL 7.x versions as RHEL 7 when building

All RHEL 7.x versions are backwards compatible with each other. A .NET
Core build from 7.2 works fin on RHEL 7.3, for example. Treat this as a
general case and handle all 7.x versions the same.

This change only affects whether packages are built or not.

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