RFR: Adapt upstream object pinning API

[Roman Kennke]

Am 04.04.2018 um 19:02 schrieb Zhengyu Gu:
> Adapted upstream object pinning API, also made adjustment to critical
> native support to use new API.
> 
> 
> Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/pin_interface/webrev.00/
> 
> Test:
> 
>   hotspot_gc_shenandoah on Linux x64 and Windows x64 (release + fastdebug)
> 
> 
> Thanks,
> 
> -Zhengyu

I was about to merge from upstream jdk/jdk in the next few days. Maybe
that would get it in anyway?

Roman