RFR (T) 8230116: Test workaround to Klass::_class_loader_data sometimes NULL problem

[coleen.phillimore at oracle.com]

Summary: This is a low frequency problem that we are seeing internally, 
this patch is mostly to rule out one theory.

Tested locally on my machine.

open webrev at http://cr.openjdk.java.net/~coleenp/2019/8230116.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8230116

Thanks,
Coleen