RFR[8u]: Fix force termination detection by spin master

[Aleksey Shipilev]

On 10/18/2018 08:48 PM, Zhengyu Gu wrote:
> Aleksey discovered JVM hung during backporting recent Shenandoah OWST terminator fix to correct
> force termination logic. Apparently, our 8u port is broken all alone, missing force termination
> detection by spin master.
> 
> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/8u_force_termination/webrev.00/

Looks good!

-Aleksey