Can be always enabled
* TaskState.java: Handle .processPerformTerminating in
startRunning, and zombied states. Do not pass the terminating
exit status to Task .sendContinue.
* LinuxTask.java: Always enable exit tracing.
* Task.java: Delete .traceExit.
* Task.java: Merge .performExited into .performTerminated.
Replace .performExiting into .performTerminating.
* LinuxHost.java: Update.
* TaskState.java: Replace .processPerformExiting with
.processPerformTerminating. Merge .processPerformExited into
* TestLib.java, LinuxHost.java: Update Wait .Observer objects so
that .eventExit has additional signal, and coreDumped parameters,
and .exited is merged into .terminated.
* TaskObserver.java: Replace .Exiting with .Terminating; Merge
.Exited into .Terminated.