RFR 8199868: Support JNI critical functions in object pinning API

[Zhengyu Gu]

Hi Andrew,

On 07/09/2018 09:57 AM, Andrew Haley wrote:
> On 06/15/2018 12:55 PM, Zhengyu Gu wrote:
>> Ping!!!! anyone? please!
> 
> How did you test this?  Do you have code that exercises the interface?
> If so, please put it on cr.openjdk.
> 

So far, only Shenandoah supports object pinning API, so there are a 
couple of jtreg tests in Shenandoah repos:

gc/shenandoah/CriticalNativeArgs.java
gc/shenandoah/CriticalNativeStress.java


Thanks,

-Zhengyu