RFR 8069048: (process) Suspend finishing threads when process exits [win]

[Ivan Gerasimov]

Hello everyone!

This is yet another iteration in the attempt to solve the 'wrong exit 
code' bug on Windows [1].
The wrong exit code has been observed once again with one of the 
regression tests.

The suspicion is that this might be due to the critical section had been 
destroyed before all the children threads were terminated.
In that case, one of the threads had been unblocked and called 
_endthreadex(), which resulted in a race.

To address this scenario, it is proposed to make the thread that is 
about to exit the process raise a flag.
If the flag is raised, any threads wishing to exit should instead 
suspend themselves.

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8069048
WEBREV: http://cr.openjdk.java.net/~igerasim/8069048/0/webrev/

[1] https://bugs.openjdk.java.net/browse/JDK-6573254

Sincerely yours,
Ivan