check that VM set pAddr == nullptr (#15003)
check that VM set pAddr == nullptr (#15003)

When VM returns addr != nullptr from getHelperFtn, it must set pAddr to nullptr.
cshung/coreclr,mmitche/coreclr,wtgodbe/coreclr,mmitche/coreclr,cshung/coreclr,poizan42/coreclr,poizan42/coreclr,krk/coreclr,JosephTremoulet/coreclr,mmitche/coreclr,JosephTremoulet/coreclr,mmitche/coreclr,mmitche/coreclr,ruben-ayrapetyan/coreclr,krk/coreclr,JosephTremoulet/coreclr,wtgodbe/coreclr,wtgodbe/coreclr,cshung/coreclr,wtgodbe/coreclr,krk/coreclr,ruben-ayrapetyan/coreclr,ruben-ayrapetyan/coreclr,yizhang82/coreclr,wtgodbe/coreclr,poizan42/coreclr,yizhang82/coreclr,poizan42/coreclr,JosephTremoulet/coreclr,mmitche/coreclr,poizan42/coreclr,krk/coreclr,krk/coreclr,wtgodbe/coreclr,cshung/coreclr,ruben-ayrapetyan/coreclr,ruben-ayrapetyan/coreclr,yizhang82/coreclr,cshung/coreclr,JosephTremoulet/coreclr,JosephTremoulet/coreclr,yizhang82/coreclr,cshung/coreclr,poizan42/coreclr,yizhang82/coreclr,krk/coreclr,yizhang82/coreclr,ruben-ayrapetyan/coreclr