RFR: Simplify JNI critical support

[Roman Kennke]

Moved test from subdir to just test/gc/shenandoah and renamed
hotspot_fast_gc_shenandoah test group to just hotspot_gc_shenandoah
(tests may not be that fast ;-) )

http://cr.openjdk.java.net/~rkennke/jni_critical/webrev.02/

Ok?

Roman

Am Mittwoch, den 21.09.2016, 13:10 +0200 schrieb Roman Kennke:
> This implements Zhengyu's idea to simply pin heap regions that
> contain
> active JNI critical arrays, i.e. those regions would not enter the
> collection set.
> 
> This makes our JNI critical region handling much simpler. We no
> longer
> have to bail and retry on active critical regions (like other GCs).
> Most importantly, we can get rid of the complicated locking dance
> between Java threads, the VM thread and GC threads that has plagued
> us
> in the past.
> 
> I also added a regression test to verify this is handled correctly,
> together with some infrastructure to build & run Shenandoah tests
> only
> by invoking:
> 
> make test TEST="hotspot_fast_gc_shenandoah"
> 
> http://cr.openjdk.java.net/~rkennke/jni_critical/webrev.00/
> 
> Ok to push?
> 
> Roman
>