RFR: Apply ShenandoahEvacOOMScope only for evac-taking paths in ShenandoahBarrierSet

[Roman Kennke]

Am 18.06.2018 um 17:00 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/sbs-oomscope/webrev.01/
> 
> There is no need to penalize non-traversal GC with entering evac-scope, because those paths are not
> evacuating anything. I inverted the nested branches to highlight that we only need to do this for
> traversal paths.
> 
> Testing: tier3_gc_shenandoah
> 
> Thanks,
> -Aleksey
> 


Looks good. Thanks!
Roman