RFR: Fix freeze when running OOM during write barrier

[Aleksey Shipilev]

On 12/15/2016 04:58 PM, Roman Kennke wrote:
> We sometimes freeze when a write-barrier runs out of memory. Reason is
> the recent refactoring in our driver thread: we would skip turning off
> evacuation, however Java threads are waiting for this to happen.
> They'll wait indefinitely, and thus never return to a safepoint.
> 
> http://cr.openjdk.java.net/~rkennke/fixfreeze/webrev.00/

Yes. Sorry about this.

-Aleksey