Avoid clobbering FldSeq annotations in cloneExpr
Avoid clobbering FldSeq annotations in cloneExpr

The overload of cloneExpr that takes a variable number and value to
perform replacements is intended to be used by the loop unroller, which
runs between Morph (where FldSeq annotations are generated) and value
numbering (where FldSeq annotations are consumed).  Update that codepath
to call `LabelIndex` when replacing a `GTF_VAR_ARR_INDEX` node, and to
avoid calling `gtFoldExpr` (which does not preserve these annotations).
Downstream constant folding should be capable of doing that optimization.

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