RFR: 8000973: SA on windows thread inspection is broken

[Yumin Qi]

Please have your comments on:

http://cr.openjdk.java.net/~minqi/8000973/

This only affected Windows platform.

Summary: After bug 7161732, On Windows SA could not find correct address 
of thread_id of OSThread since _thread_id moved to end of the class . 
The presupposition of the address is following thread handle no longer 
stands. Fix by adding thread_id field to OSThread and getting the  
address directly from OSThread.
Reviewed-by:
Contributed-by: yumin.qi at oracle.com

Thanks
Yumin