Review Request JDK-8189193: FindClass mistakenly uses system class loader when the initiating loader is bootstrap loader

[mandy chung]

This is a regression caused by JDK-8188052. FindClass should only use 
system class loader when there is no caller class or when it's called 
from JNI_OnUnload.  When there is a caller class, it should either use 
its class loader or the one associated with JNI_Onload.

Webrev:
http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8189193/webrev.00/

JBS:https://bugs.openjdk.java.net/browse/JDK-8189193

thanks
Mandy