RFR: Avoid stub when calling to write-barrier from C2, remove all related code

[Roman Kennke]

If it's not otherwise useful, then yes, feel free to withdraw it.

Thanks, Roman

Am 20. November 2018 09:40:51 MEZ schrieb Roland Westrelin <rwestrel at redhat.com>:
>
>Should I withdraw JDK-8213528 from review upstream, then?
>
>Roland.