RFR: Implementation of JEP 387: Elastic Metaspace (round two)

[Leo Korinth]

> 
> Finally, why was it chosen that each node could carry precisely two
> chunk-roots? It seems somewhat easier to have a one-to-one relation
> between chunk-root and VirtualSpaceNode (when we are already so close
> to one).
> 

Answering to myself: Because of compressed class space of course. Then we
could no longer have one huge VirtualSpaceNode for compressed space, and
VirtualSpaceList would need extra logic for allocating into the compressed
class address space. Or we would need more levels for the buddy allocator
in compressed class space so that it could still be one huge node (with a
huge root-chunk). Each of which is a non-trivial change.

Sorry for my confusion.

Thanks,
Leo