RFR(S): 8189368: Add information on current bias holder for BiasedLockRevocation event

[Erik Gahlin]

Looks good.

Erik
> Hi all,
>
> Please review the following changes which add a new field to the BiasedLockRevocation event, previousOwner, containing information on which thread (if any) owned the bias before it was revoked.
>
> Issue:
> https://bugs.openjdk.java.net/browse/JDK-8189368
>
> Webrev:
> http://cr.openjdk.java.net/~egahlin/8189368_1/
>
> Best regards,
> Robin