Keep track of per-cycle mutator/collector allocs. Fix mutator/collector alloc region overlap in traversal.

[Aleksey Shipilev]

On 03/16/2018 10:20 PM, Roman Kennke wrote:
> Ok, I bite the bullet and implement that scheme:
> http://cr.openjdk.java.net/~rkennke/traversal-alloc-region/webrev.04/
> 
> It starts out with 100%mutator/0%collector regions, and then steals from
> the other set if depleted.
> 
> Please review carefully. I am not sure I've always got the index
> bookkeeping correct.

It seems correct.

Quite a bit of refactoring to streamline the code:
  http://cr.openjdk.java.net/~shade/shenandoah/freeset-split-bitmaps/webrev.01/

Passes hotspot_gc_shenandoah

-Aleksey