[12] RFR 8129310: java/net/Socket/asyncClose/AsyncClose.java fails intermittently

[Chris Yin]

Please review below minor change for java/net/Socket/asyncClose/AsyncClose.java fails intermittently issue, thanks

From previous failure log, seems lack of enough info to find out root cause, this change is to enhance a little to base test class AsyncCloseTest with guessing, even it may not completely address the issue, additional log info should still helpful for future debugging.

1. add volatile to 'boolean passed' and 'boolean closed' to avoid any visibility issue since they were write/read in different threads
2. failure reason info may be overwritten if failed() been called multiple times, change it to record all failure messages.

bug: https://bugs.openjdk.java.net/browse/JDK-8129310
webrev: http://cr.openjdk.java.net/~xyin/8129310/webrev.00/

Regards,
Chris