RFR: 8215097: Do not create NonJavaThreads before BarrierSet

[Thomas Schatzl]

Hi,

On Sun, 2018-12-09 at 03:30 -0500, Kim Barrett wrote:
> Please review this change to move the construction of some work gang
> threads by G1 and CMS to after they've created the barrier set.  This
> allows the removal of some bootstrapping code needed to support that
> construction order.  There isn't any requirement for the old order,
> it seems to just be a historical artifact.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8215097
> 
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8215097/open.00/
> 
> Testing:
> mach5 tier1-5

  looks good.

Thomas