hg: jdk/sandbox: 8238676: jni crashes on accessing it from process exit hook

[chris.hegarty at oracle.com]

Changeset: 80e4a066342d
Author:    dholmes
Date:      2020-03-02 19:49 -0500
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/80e4a066342d

8238676: jni crashes on accessing it from process exit hook
Reviewed-by: fparain, gziemski

! make/test/JtregNativeHotspot.gmk
! src/hotspot/share/prims/jni.cpp
+ test/hotspot/jtreg/runtime/jni/atExit/TestAtExit.java
+ test/hotspot/jtreg/runtime/jni/atExit/libatExit.c