RFR: Integrate upstream OWST task terminator to Shenandoah

[zgu at redhat.com]

Fixed webrev link:

http://cr.openjdk.java.net/~zgu/shenandoah/upstream_owst/webrev.01/

-Zhengyu

On Fri, 2018-12-07 at 11:36 -0500, zgu at redhat.com wrote:
> Upstream "JDK-8214458: Port ShenandoahTaskTerminator to mainline and
> make it default" has been reviewed and is ready for pushing once CSR
> is
> approved.
> 
> Let's get a head start and review Shenandoah side of change based on
> latest JDK-8214458 patch.
> 
> 
> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/upstream_owst/webr
> ev
> .01/
> 
> Test:
>   tier1, tier2 and tier3 gc_shenandoah
>   fastdebug and release
> 
> Thanks,
> 
> -Zhengyu