8218812: vmTestbase/nsk/jvmti/GetAllThreads/allthr001/TestDescription.java failed

[Daniil Titov]

Please review a change that fixes this test.

The problem here is that the test checks the number of threads and with Graal on additional threads the test doesn't expect are started and cause the test fail.

The fix introduces a new capability " can_show_compiler_threads" that affects whether Java compiler threads are retuned with JVMTI GetAllThreads call. By default this capability is off. The fix also adds " HotSpotGraalManagement Bean Registration" thread to the list of the threads the tests must ignore.

Webrev: http://cr.openjdk.java.net/~dtitov/8218812/webrev.01 
Bug: https://bugs.openjdk.java.net/browse/JDK-8218812 

Mach5 tier1, tier2 and tier3 tests successfully passed with this change.

Thanks!
-Daniil