RFR [sh/8u]: Backport elimination of forwarding pointer

[Roman Kennke]

> On 10/28/19 6:06 PM, Roman Kennke wrote:
>> Ha, and it missed the webrev link:
>>
>> http://cr.openjdk.java.net/~rkennke/nofwdptr-sh8/webrev.00/
> 
> From the first cursory examination, looks really good. It builds fine and passes
> hotspot_gc_shenandoah on my machine. But, I think it misses two important followup bugfixes:
>  https://bugs.openjdk.java.net/browse/JDK-8231583
>  https://bugs.openjdk.java.net/browse/JDK-8231197

I also backported the two:

Incremental:
http://cr.openjdk.java.net/~rkennke/nofwdptr-sh8/webrev.01.diff/
Full:
http://cr.openjdk.java.net/~rkennke/nofwdptr-sh8/webrev.01/

Testing: same as before, plus the tests mentioned in the bugreports. All
good.

Roman