RFR(S) : 8203238: [TESTBUG] rewrite MemOptions shell test in Java

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8203238/webrev.00
> 330 lines changed: 91 ins; 236 del; 3 mod; 

Hi all,

could you please review this small patch which rewrites MemOptions shell test?

while porting the test, I noticed that available memory checks aren't required, and the test successfully passes even w/o them, so the java version of the test doesn't check available memory and only @requires 64 bits vm. given the test doesn't require lots of time/resources to execute, I've also removed it from exclusiveAccess. MemStat class was made static inner class of MemOptionsTest for the sake of readability and brevity.

webrev: http://cr.openjdk.java.net/~iignatyev//8203238/webrev.00
testing: the changed tests multiple tests on {linux, windows, mac} w/ {SerialGC,ZGC,G1GC,ParallelGC}
JBS: https://bugs.openjdk.java.net/browse/JDK-8203238

NB the shell version of the test had a bug which prevent its execution. an incorrect operator (:=) was used at L#23,23, which led to bogus 'java' variable at L#44 and non zero exit code at L#48, so the test passes w/ 'Skipping the test; a 64-bit VM is required.' message on all platforms. so this patch effectively resurrects the test.

Thanks,
-- Igor