RFR: Update counters on slow-path more rarely

[Aleksey Shipilev]

On 08/30/2017 07:06 PM, Aleksey Shipilev wrote:
> Running with -UseTLAB, thus stressing shared allocations, is slow because we update the counters
> even for the minuscule shared allocations. It makes sense to do this only when new region is claimed
> during shared alloc.
> 
> Fix:
>   http://cr.openjdk.java.net/~shade/shenandoah/alloc-lazier-counters/webrev.01/

Better handling humongous allocs:
 http://cr.openjdk.java.net/~shade/shenandoah/alloc-lazier-counters/webrev.02/

-Aleksey