hg: jdk/jdk: 8193780: (ref) Remove the undocumented "jdk.lang.ref.disableClearBeforeEnqueue" system property

[mandy.chung at oracle.com]

Changeset: 2731c0ee46a9
Author:    mchung
Date:      2017-12-21 15:04 -0800
URL:       http://hg.openjdk.java.net/jdk/jdk/rev/2731c0ee46a9

8193780: (ref) Remove the undocumented "jdk.lang.ref.disableClearBeforeEnqueue" system property
Reviewed-by: alanb

! src/java.base/share/classes/java/lang/ref/Reference.java
! test/jdk/java/lang/ref/ReferenceEnqueue.java