RFR(S) : 8252522 : nsk/share/test/StressOptions should multiple stressTime by jtreg's timeout-factor

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev/8252522/webrev.01/
> 118 lines changed: 32 ins; 36 del; 50 mod; 

Hi all,

could you please review this small patch which updates StressOptions to adjust allocated time according to TIMEOUT_FACTOR?

from JBS:
> nsk/share/test/StressOptions and Stresser aren't aware of jtreg's timeout-factor and hence don't provide enough stress time for testing in slow/stress configurations, e.g. Xcomp.

the patch also includes small clean up and refactoring, such as removal of unused c-tor and using switch instead if-elif. webrev w/o these changes -- http://cr.openjdk.java.net/~iignatyev/8252522/webrev.00/

webrev: http://cr.openjdk.java.net/~iignatyev/8252522/webrev.01/
JBS: https://bugs.openjdk.java.net/browse/JDK-8252522
testing: vmTestbase tests (in progress)

Thanks,
-- Igor