RFR (T) 8229894: SEGV during class loading in InstanceKlass::print_class_load_logging

[coleen.phillimore at oracle.com]

Summary: NULL initialize decorations that are not used to make crash 
easier to understand next time.

This doesn't fix the bug (I can't find or reproduce it), but might be 
helpful for debugging if it happens again.

Tested with tier1 all Oracle platforms, and tier2,3 linux-x64-debug.

open webrev at http://cr.openjdk.java.net/~coleenp/2019/8229894.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8229894

Thanks,
Coleen