hg: valhalla/valhalla: 8241704: Add test case for unloadable class with nest host error

[david.holmes at oracle.com]

Changeset: c964a558522d
Author:    dholmes
Date:      2020-03-30 19:25 -0400
URL:       https://hg.openjdk.java.net/valhalla/valhalla/rev/c964a558522d

8241704: Add test case for unloadable class with nest host error
Reviewed-by: mchung

+ test/hotspot/jtreg/runtime/Nestmates/membership/Helper.java
+ test/hotspot/jtreg/runtime/Nestmates/membership/TestNestHostErrorWithClassUnload.java