RFR(XXS): 8155092: [TESTBUG] TestHumongousClassLoader.java needs UnlockDiagnosticVMOptions before WhiteBoxAPI

[Kirill Zhaldybin]

Dear all,

Could you please review this very small fix for 8155092?

I added missing -XX:+UnlockDiagnosticVMOptions to the test so it will 
work on product builds.

CR: https://bugs.openjdk.java.net/browse/JDK-8155092
WebRev: http://cr.openjdk.java.net/~kzhaldyb/webrevs/JDK-8155092/webrev.00/

Thank you.

Regards, Kirill