RFR(xs): JDK-8171046 - Quarantine TestStressG1Humongous.java until JDK-8171045 is fixed

[Jesper Wilhelmsson]

Hi,

Please review this tiny change to quarantine a test that is failing in the 
hotspot nightly.

Bug: https://bugs.openjdk.java.net/browse/JDK-8171046
Webrev: http://cr.openjdk.java.net/~jwilhelm/8171046/webrev.00/

Thanks,
/Jesper