RFR: 8183137: [MVT] C2 doesn't eliminate redundant value type allocations inside loops

[Roland Westrelin]

> Right, that's basically what Vladimir I. mentioned as well in another thread:

Yes. it's very similar to what Vladimir suggested. The main difference
is that I make sure we always have a valid oop input edge for a
ValueTypePtrNode so if elimination of allocation fails, we can fall back
to already allocated values.

Roland.