RFR: 8234383: Test TestBiasedLockRevocationEvents.java assumes -XX:UseBiasedLocking is enabled

[Per Liden]

Hi,

Please review this one-liner test fix.

The test TestBiasedLockRevocationEvents.java assumes 
-XX:UseBiasedLocking is enabled. While this is generally true, it's not 
true when e.g. enabling ZGC. There's also work ongoing to look into 
disabling it by default (JDK-8231264). The test should supply 
-XX:+UseBiasedLocking on the run line to avoid making assumptions about 
if it's enabled by default or not.

Bug: https://bugs.openjdk.java.net/browse/JDK-8234383
Webrev: http://cr.openjdk.java.net/~pliden/8234383/webrev.0

/Per