RFR (XS): -ShenandoahSATBBarrier disables matrix updates

[Roman Kennke]

Am 20.03.2017 um 16:40 schrieb Aleksey Shipilev:
> Hi,
>
> While studying the generated code, I realized that -ShenandoahSATBBuffer
> disables matrix updates too. Oops. This does not affect our performance runs
> just yet, because we enable SATB barriers before enabling matrix barriers. We
> should fix this oddity nevertheless:
>  http://cr.openjdk.java.net/~shade/shenandoah/satb-barriers-disable-2/webrev.01/
>
> Testing: hotspot_gc_shenandoah, eyeballing assembly
>
> Thanks,
> -Aleksey
>
ok