RFR: Cleanup allocation tracking in heuristics

[Aleksey Shipilev]

On 03/02/2018 12:40 PM, Aleksey Shipilev wrote:
> http://cr.openjdk.java.net/~shade/shenandoah/heuristics-bytes-allocated/webrev.01/
> 
> This cleans up allocation tracking in heuristics. Most of the things are not used and bit-rotted
> over the last year. The one thing that is still important to us -- bytes allocated since last cycle
> -- is updated racily, and thus is unreliable.

Actually, acquiring the ShHeapLock for resetting a single flag in ShConcThread is probably too
excessive, as it has the potential to delay the first STW that dives into the cycle.

Rewritten that with atomics:
  http://cr.openjdk.java.net/~shade/shenandoah/heuristics-bytes-allocated/webrev.02/

-Aleksey