RFR 8058927: ATG throws ClassNotFoundException

[Kevin Walls]

Hi,

This is already in 8u, I'd like to get a review of this backport for 7u, 
as it isn't quite the same as the original fix.

webrev
http://cr.openjdk.java.net/~kevinw/8058927/webrev.00/

bug
https://bugs.openjdk.java.net/browse/JDK-8058927

I had to put a check for null in objArrayKlass::class_loader(), as it is 
called from Universe::fixup_mirrors  at startup time.

JPRT, the testcase shown here and the original test that found the 
problem have tested OK.

Thanks
Kevin