Fix race condition in setting ReferenceCountedOpenSslEngine.needTask flag

[kwart]

Fixes #12139

What's changed

This PR reorders resetting ReferenceCountedOpenSslEngine.needTask flag within the io.netty.handler.ssl.ReferenceCountedOpenSslEngine.TaskDecorator.run() method. The flag shouldn't be unset before the task execution finishes.

What's not changed

This PR doesn't change the needTask flag handling in AsyncTasks. I'm not sure when and how this type is used.

There could be also a problem if more tasks are allowed to be returned for subsequent getDelegatedTask() call.

    List<Runnable> collectTasks(SSLEngine sslEngine) {
        List<Runnable> tasks = new LinkedList<Runnable>();
        Runnable task;
        while ((task = sslEngine.getDelegatedTask()) != null) {
            tasks.add(task);
        }
        return tasks;
    }

Then the single boolean variable is not enough to track task processing. It would rather deserve a task counter.

[chrisvest]

It was specifically changes to this in #11739 because there are other issues if the task in question inspects the needTask field.
I don't recall the details of that, but just saying there's more going on and we shouldn't fix one bug by bringing back another.

[normanmaurer]

Let me investigate...

[normanmaurer]

working on this now

[normanmaurer]

closing... This is replaced by #12149