RFR: 8242239: [Graal] javax/management/generified/GenericTest.java fails: FAILED: queryMBeans sets same

[Daniil Titov]

Please review the change that fixes the failure of javax/management/generified/GenericTest.java  and
 javax/management/query/CustomQueryTest.java tests when Graal is on.

The tests checks that calls of management API are consistent and return the same set of MBeans.  However, 
when Graal is on the Graal MBean might be registered between the calls that in turn makes the results 
inconsistent and the tests fail.

The fix makes the test aware that some MBean might be registered while the checks run and if it happens the tests repeat the check.

Testing : Mach5 tests with Graal on and tier1-tier3 tests passed.

[1]  http://cr.openjdk.java.net/~dtitov/8242239/webrev.01/ 
[2] https://bugs.openjdk.java.net/browse/JDK-8242239 

Thanks,
Daniil