RFR: Explicit concurrent GC should do traversal when Traversal GC is enabled

[Roman Kennke]

Am 20.03.2018 um 18:59 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/traversal-explicit-gc/webrev.01/
> 
> If user supplies -XX:+ExplicitGCInvokesConcurrent when "traversal" is enabled, and the application
> calls System.gc(), we would enter normal concurrent cycle. Which is obviously not what we want, at
> all (it should go down in flames, actually).
> 
> Testing: hotspot_gc_shenandoah, added test cases
> 
> Thanks,
> -Aleksey
> 

Yep, go for it!
Roman