Allow creation of variables of TYP_STRUCT with non-value class handles.
Allow creation of variables of TYP_STRUCT with non-value class handles.

Variables of TYP_STRUCT with non-value class handles represent stack-allocated objects.
Temporarily disable promotion of fields of stack-allocated objects.

krk/coreclr,cshung/coreclr,mmitche/coreclr,poizan42/coreclr,cshung/coreclr,cshung/coreclr,poizan42/coreclr,cshung/coreclr,wtgodbe/coreclr,wtgodbe/coreclr,poizan42/coreclr,mmitche/coreclr,wtgodbe/coreclr,cshung/coreclr,wtgodbe/coreclr,krk/coreclr,krk/coreclr,krk/coreclr,wtgodbe/coreclr,poizan42/coreclr,mmitche/coreclr,krk/coreclr,wtgodbe/coreclr,mmitche/coreclr,poizan42/coreclr,mmitche/coreclr,mmitche/coreclr,krk/coreclr,poizan42/coreclr,cshung/coreclr