RFR: OWST implementation

[Zhengyu Gu]

This is the initial implementation of OWST, which is pretty closely following Google's paper.

I intend to minimize the changes in the changeset, due to recent regression SPECjbb number.
I think there are areas we can improve the implementation. For example, to have spin master give up
its role before goes into sleep, so other worker who detects new tasks, may wake up waiting workers, etc.


Webrev: http://cr.openjdk.java.net/~zgu/owst/webrev.00/

Thanks,

-Zhengyu