RFR: 8290482: Update JNI Specification of DestroyJavaVM for better alignment with JLS, JVMS, and Java SE API Specifications

[David Holmes]

This update is primarily about changes to the JNI Invocation API specification, mainly in relation to `DestroyJavaVM`. The motivation for the changes is to align with changes being made to the JLS, JVMS and `java.lang.Runtime`, specifications in relation to VM termination - ref:

JDK-8290196 12.8: Clarify the definition of program exit
https://bugs.openjdk.org/browse/JDK-8290196

JDK-8290388 5.7: Clarify the definition of JVM termination
https://bugs.openjdk.org/browse/JDK-8290388

JDK-8290036 Define and specify Runtime shutdown sequence
https://bugs.openjdk.org/browse/JDK-8290036

Mostly these are just non-normative changes to the JNI spec prose but there are two actual specification changes:

1.  The fact it is an error to detach a thread with active Java frames was only mentioned in the overview section, not in the actual `DetachCurrentThread` specification. (Just an oversight - the VM already checked this)

2.  We need to make it an error to call `DestroyJavaVM` from an attached thread with active Java frames (as this can't work for the same reason we disallow `DetachCurrentThread`). This requires an implementation change in Hotspot.

Issue 2 covers the code change, and regression test, in this PR.

In addition the specification changes can be seen here:

- specdiff: http://cr.openjdk.java.net/~dholmes/8290482/8290482-jni-spec/diff.html
- original: http://cr.openjdk.java.net/~dholmes/8290482/8290482-jni-spec/jni-invocation-original.html
- new: http://cr.openjdk.java.net/~dholmes/8290482/8290482-jni-spec/jni-invocation-new.html

The specification itself is not open but comments on the spec changes are welcome - though please see the JBS issue and CSR request first. The revised wording has already been extensively reviewed/negotiated between Alex Buckley, Stuart Marks and myself, so any change must either be a glaring error/problem or else a trivial adjustment.

Thank you.

-------------

Commit messages:
 - Fix code format
 - Fix code format
 - Fix @bug number
 - Merge branch 'master' into 8290482-destroyjvm
 - Added testcase
 - 8290482: Update JNI Specification of DestroyJavaVM for better alignment with JLS, JVMS, and Java SE API Specifications

Changes: https://git.openjdk.org/jdk/pull/10352/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10352&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290482
  Stats: 110 lines in 4 files changed: 108 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10352.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10352/head:pull/10352

PR: https://git.openjdk.org/jdk/pull/10352