RFR: 8210321: Create NO_KEEPALIVE CLD holder accessor

[Kim Barrett]

> On Sep 3, 2018, at 10:38 AM, Erik Österlund <erik.osterlund at oracle.com> wrote:
> 
> Hi,
> 
> In order to perform concurrent class unloading, ZGC needs a way to peek the holder without keeping it alive.
> 
> Webrev:
> http://cr.openjdk.java.net/~eosterlund/8210321/webrev.00/
> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8210321
> 
> Thanks,
> /Erik

Looks good.

It’s unfortunate that something like this needs to be public.