RFR: 8u40: Thread and management extension support

[John Coomes]

Stefan Johansson (stefan.johansson at oracle.com) wrote:
> Hi,
> 
> Please review these changes to allow thread and management extensions in 
> the VM.
> http://cr.openjdk.java.net/~sjohanss/thread-ext/webrev.00/
> 
> There is currently no JBS issue open for this issue but one will be open 
> shortly.

Looks good to me.

FWIW, I don't care too much for the "break" in
Threads::find_java_thread_from_java_tid() (line 3891); it should
instead be "return thread".  But since this code is just being moved
verbatim from management.cpp, it's ok to leave as is.

-John