RFR [8]: Excess barriers before JNI accesses, already covered by "Move barriers into typeArrayOop.hpp direct memory accessors"

[Roman Kennke]

> http://cr.openjdk.java.net/~shade/shenandoah/8u-jni-barriers/webrev.01/
> 
> Found this while cross-referencing integration repo and sh/jdk8u. It seems to me these barriers are
> excessive, because they would be all redone when doing typeArrayOop::*_at_addr accessor. This is
> partially done by our previous change:
>   http://hg.openjdk.java.net/shenandoah/jdk8u/hotspot/rev/a8d83c1c5fce
> 
> ...and the patch above seems to complete it.
> 
> Testing: tier3_gc_shenandoah {fastdebug|release}

Looks correct. Thanks!
Roman