MINOR: task: move the nice field to the struct task only

The nice field isn't needed anymore for the tasklet so we can move it
from the TASK_COMMON area into the struct task which already has a
hole around the expire entry.
diff --git a/include/haproxy/task-t.h b/include/haproxy/task-t.h
index 4661715..e8391ca 100644
--- a/include/haproxy/task-t.h
+++ b/include/haproxy/task-t.h
@@ -115,7 +115,7 @@
 #define TASK_COMMON							\
 	struct {							\
 		unsigned short state; /* task state : bitfield of TASK_	*/ \
-		short nice; /* task prio from -1024 to +1024 */ \
+		/* 16-bit hole here */ \
 		unsigned int calls; /* number of times process was called */ \
 		struct task *(*process)(struct task *t, void *ctx, unsigned short state); /* the function which processes the task */ \
 		void *context; /* the task's context */			\
@@ -128,6 +128,8 @@
 	struct eb32sc_node rq;		/* ebtree node used to hold the task in the run queue */
 	struct eb32_node wq;		/* ebtree node used to hold the task in the wait queue */
 	int expire;			/* next expiration date for this task, in ticks */
+	short nice;                     /* task prio from -1024 to +1024 */
+	/* 16-bit hole here */
 	unsigned long thread_mask;	/* mask of thread IDs authorized to process the task */
 	uint64_t call_date;		/* date of the last task wakeup or call */
 	uint64_t lat_time;		/* total latency time experienced */
diff --git a/include/haproxy/task.h b/include/haproxy/task.h
index 8f70f5b..a3aed15 100644
--- a/include/haproxy/task.h
+++ b/include/haproxy/task.h
@@ -441,7 +441,6 @@
  */
 static inline void tasklet_init(struct tasklet *t)
 {
-	t->nice = 0;
 	t->calls = 0;
 	t->state = TASK_F_TASKLET;
 	t->process = NULL;