RFR: Beef up and parallelize EvilSyncBug test

[Zhengyu Gu]

Good to me.

-Zhengyu

On 10/02/2018 11:55 AM, Aleksey Shipilev wrote:
> http://cr.openjdk.java.net/~shade/shenandoah/tests-evilsyncbug/webrev.01/
> 
> This helped to capture shutdown deadlocks in sh/jdk8u, especially when running EvilSyncBug as the
> standalone test. The test is time sensitive, and it enjoys competition with other tests, or even itself.
> 
> Testing: tier3_gc_shenandoah
> 
> Thanks,
> -Aleksey
>