Enable implicit byref struct promotion
Enable implicit byref struct promotion

Remove the artificial limitation marking them address-taken.  Add a
hueristic that avoids promoting if there are too few references to the
parameter.

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