RFR: 8189359: Move native weak oops cleaning out of ReferenceProcessor

[Kim Barrett]

> On Oct 18, 2017, at 7:55 AM, Stefan Karlsson <stefan.karlsson at oracle.com> wrote:
> 
> Hi all,
> 
> Updated webrevs:
> http://cr.openjdk.java.net/~stefank/8189359/webrev.03.delta
> http://cr.openjdk.java.net/~stefank/8189359/webrev.03

Looks good.