RFR: Avoid write barrier during full GC

[Roman Kennke]

Ok.

Context (from IRC): jvmti rehashing runs into WB during full GC, which doesn't work. This change makes wb symmetrical to rb.

Roman


Am 31. Oktober 2018 20:50:18 MEZ schrieb Zhengyu Gu <zgu at redhat.com>:
>This one line change to avoid write barrier during full GC.
>
>Webrev: 
>http://cr.openjdk.java.net/~zgu/shenandoah/avoid_wb_full_gc/weberv.00/
>
>
>Test:
>   tier3_gc_shenandoah (fastdebug and release)
>
>Thanks,
>
>-Zhengyu