RFR(S) : 8199265 : java/util/Arrays/TimSortStackSize2.java fails with OOM

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev/8199265/webrev.00/
> 10 lines changed: 0 ins; 2 del; 8 mod;

Hi all

could you please review another attempt to make TimSortStackSize2 more robust?

8190679 changed the test to set both Xmx and Xms to avoid failures caused by Xmx being smaller than Xms (when Xmx is specified as external vm flag). it appears that current values of heap size might not be enough in some cases, therefore setting Xmx equal to Xms leads to OOM. 

The proposed fix sets Xmx two times more than Xms, this should be enough for the test to pass and also ensures that Xmx is always bigger than Xms (since the test specific flags are appended, external Xms/Xmx flags will be ignored). 

JBS: https://bugs.openjdk.java.net/browse/JDK-8199265
webrev: http://cr.openjdk.java.net/~iignatyev/8199265/webrev.00/
testing:  java/util/Arrays/TimSortStackSize2.java multiple times on different platforms

Thanks,
-- Igor