MINOR: task: add a new pointer to current tasklet queue

In task_per_thread[] we now have current_queue which is a pointer to
the current tasklet_list entry being evaluated. This will be used to
know the class under which the current task/tasklet is currently
running.
diff --git a/src/task.c b/src/task.c
index 2097555..1f7fd53 100644
--- a/src/task.c
+++ b/src/task.c
@@ -330,6 +330,7 @@
 	void *ctx;
 	int done = 0;
 
+	sched->current_queue = list;
 	while (done < max && !LIST_ISEMPTY(list)) {
 		t = (struct task *)LIST_ELEM(list->n, struct tasklet *, list);
 		state = (t->state & (TASK_SHARED_WQ|TASK_SELF_WAKING));
@@ -400,6 +401,8 @@
 		}
 		done++;
 	}
+
+	sched->current_queue = NULL;
 	return done;
 }