MINOR: task: only check TASK_WOKEN_ANY to decide to requeue a task

MINOR: task: only check TASK_WOKEN_ANY to decide to requeue a task

After processing a task, its RUNNING bit is cleared and at the same time
we check for other bits to decide whether to requeue the task or not. It
happens that we only want to check the TASK_WOKEN_* bits, because :
  - TASK_RUNNING was just cleared
  - TASK_GLOBAL and TASK_QUEUE cannot be set yet as the task was running,
    preventing it from being requeued

It's important not to catch yet undefined flags there because it would
prevent addition of new task flags. This also shows more clearly that
waking a task up with flags 0 is not something safe to do as the task
will not be woken up if it's already running.