RFR: 8293592: Remove JVM_StopThread, stillborn, and related cleanup

[David Holmes]

Now that Thread.stop has been degraded to throw `UnsupportedOperationException` (JDK-8299610) the only direct source of async exceptions is from JVMTI `StopThread`. We can remove the `JVM_StopThread` code, remove the `stillborn` field from `java.lang.Thread` and its associated accesses from the VM, and we can stop special-casing `ThreadDeath` handling (as was done for the JDK code as part of JDK-8299610).

Note that JVMTI `StopThread` can only act on a thread that is alive, so it is no longer possible to stop a thread before it has been started.

Also note that there is a change in behaviour for JNI `ExceptionDescribe` as it no longer ignores `ThreadDeath` exceptions (not that it was ever specified to ignore them, it simply mirrored the behaviour of the default `UncaughtExceptionHandler` in `java.lang.ThreadGroup` - which also no longer ignores them so the mirroring behaviour remains the same).

Testing: tiers 1-3

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Commit messages:
 - Removal all special handling of ThreadDeath.
 - Remove all references to the stillborn field
 - Initial commit: remove JVM_StopThread
 - Merge
 - Updates to Java Thread Primitive Deprecation page
 - Repalce "it" with "victim thread"
 - Merge
 - Revert test/langtools/ProblemList.txt as jshell tests no longer rely on Thread.stop
 - become -> became in javadoc
 - Merge
 - ... and 5 more: https://git.openjdk.org/jdk/compare/01e7b881...58bfb313

Changes: https://git.openjdk.org/jdk/pull/10400/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10400&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293592
  Stats: 549 lines in 43 files changed: 134 ins; 308 del; 107 mod
  Patch: https://git.openjdk.org/jdk/pull/10400.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10400/head:pull/10400

PR: https://git.openjdk.org/jdk/pull/10400