Fix LSRA enregisterLocalVars
Fix LSRA enregisterLocalVars

We don't bother with the parts of LSRA that deal with lclVars if we have no tracked lclVars. However, we need to check that *after* liveness has run post-Lowering - otherwise we miss any lclVars created by optimizations or during Lowering.

Fix #16578

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