RFR (S) 8202669: Intermittent crash in ClassLoadingService::compute_class_size()

[coleen.phillimore at oracle.com]

Summary: Don't report classes that failed to load when reporting class 
unloading.  Remove the classes first.

Also add a NULL check for transitive_interfaces for safety, but the new 
tests pass without it and fail without the fix.

open webrev at http://cr.openjdk.java.net/~coleenp/8202669.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8202669

Tested with hs-tier1-5.

Thanks,
Coleen