hg: amber/amber: Automatic merge with jep-334

[maurizio.cimadamore at oracle.com]

Changeset: 2c83f64aa372
Author:    mcimadamore
Date:      2018-11-14 05:02 +0100
URL:       http://hg.openjdk.java.net/amber/amber/rev/2c83f64aa372

Automatic merge with jep-334

- test/jdk/java/lang/System/ClearProperty.java
- test/jdk/java/lang/System/SetPropertiesNull.java