MINOR: task: export run_tasks_from_list

This will help refine debug traces.

include/proto/task.h

@@ -608,6 +608,7 @@ struct work_list *work_list_create(int nbthread,
                                    void *arg);
 
 void work_list_destroy(struct work_list *work, int nbthread);
+int run_tasks_from_list(struct list *list, int max);
 
 /*
  * This does 3 things :

src/task.c

@@ -319,7 +319,7 @@ int next_timer_expiry()
  * the number of entries effectively processed (tasks and tasklets merged).
  * The count of tasks in the list for the current thread is adjusted.
  */
-static int run_tasks_from_list(struct list *list, int max)
+int run_tasks_from_list(struct list *list, int max)
 {
 	struct task *(*process)(struct task *t, void *ctx, unsigned short state);
 	struct task *t;