hg: jdk/jdk: 8242480: Negative value may be returned by getFreeSwapSpaceSize() in the docker

[jiefu at tencent.com]

Changeset: ed5d312d82b6
Author:    jiefu
Date:      2020-04-17 14:48 +0800
URL:       https://hg.openjdk.java.net/jdk/jdk/rev/ed5d312d82b6

8242480: Negative value may be returned by getFreeSwapSpaceSize() in the docker
Reviewed-by: sgehwolf, dholmes

! src/jdk.management/unix/classes/com/sun/management/internal/OperatingSystemImpl.java
+ test/jdk/jdk/internal/platform/docker/GetFreeSwapSpaceSize.java
+ test/jdk/jdk/internal/platform/docker/TestGetFreeSwapSpaceSize.java