staging: lustre: lnet: convert selftest to use workqueues

Instead of the cfs workitem library, use workqueues.

As lnet wants to provide a cpu mask of allowed cpus, it
needs to be a WQ_UNBOUND work queue so that tasks can
run on cpus other than where they were submitted.

This patch also exported apply_workqueue_attrs() which is
a documented part of the workqueue API, that isn't currently
exported.  lustre needs it to allow workqueue thread to be limited
to a subset of CPUs.

Acked-by: Tejun Heo <tj@kernel.org> (for export of apply_workqueue_attrs)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernel/workqueue.c

@@ -3806,6 +3806,7 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(apply_workqueue_attrs);
 
 /**
  * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug