JIT: defer constant-return merging for debug codegen (#14642)
JIT: defer constant-return merging for debug codegen (#14642)

If we merge constant returns into a common point we may lose track of sequence
points. So inhibit this when we are generating debuggable code.

Fixes #14339.
ruben-ayrapetyan/coreclr,JosephTremoulet/coreclr,wateret/coreclr,wateret/coreclr,poizan42/coreclr,krk/coreclr,mmitche/coreclr,ruben-ayrapetyan/coreclr,mmitche/coreclr,poizan42/coreclr,JosephTremoulet/coreclr,JosephTremoulet/coreclr,wateret/coreclr,mmitche/coreclr,wtgodbe/coreclr,krk/coreclr,wateret/coreclr,ruben-ayrapetyan/coreclr,krk/coreclr,cshung/coreclr,ruben-ayrapetyan/coreclr,poizan42/coreclr,wtgodbe/coreclr,cshung/coreclr,ruben-ayrapetyan/coreclr,yizhang82/coreclr,mmitche/coreclr,mmitche/coreclr,cshung/coreclr,wtgodbe/coreclr,krk/coreclr,poizan42/coreclr,krk/coreclr,cshung/coreclr,wateret/coreclr,yizhang82/coreclr,ruben-ayrapetyan/coreclr,JosephTremoulet/coreclr,wtgodbe/coreclr,mmitche/coreclr,JosephTremoulet/coreclr,krk/coreclr,wtgodbe/coreclr,poizan42/coreclr,cshung/coreclr,yizhang82/coreclr,yizhang82/coreclr,yizhang82/coreclr,yizhang82/coreclr,wtgodbe/coreclr,JosephTremoulet/coreclr,cshung/coreclr,wateret/coreclr,poizan42/coreclr