RFR: Readjust ShenandoahStrDedupStress test to avoid timeout

[Aleksey Shipilev]

On 10/05/2018 08:03 PM, Zhengyu Gu wrote:
> ShenandoahStrDedupStress test has caught quite a few hard to find bugs, cause it *really* stress GC
> subsystem, but it also prone to timeout.
> 
> This patch takes GC cycles into according during string rewriting phase, make sure that there are
> enough cycles to exercise deduplication code, but don't have to prolong the tests.
> 
> 
> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/dedup_stress_timeout/webrev.00/

*) camelCase is customary in Java:

 173   static GarbageCollectorMXBean gc_cycle_bean;

Otherwise looks good!

-Aleksey