workqueue: Pack workqueue_job_t more tightly

Reorder the fields so that the fields will be better aligned inside the
struct, reducing the total size of the struct.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>

Author: pcercuei

include/kos/workqueue.h

@@ -43,13 +43,13 @@ typedef struct workqueue workqueue_t;
     \brief   Structure describing a job for the work queue.
 */
 typedef struct workqueue_job {
-    /** \brief  Routine to call. */
-    void (*cb)(workqueue_t *queue, struct workqueue_job *job);
-
     /** \brief  Time at which the job will be processed.
                 If set to 0, the job will be set to execute immediately. */
     uint64_t time_ms;
 
+    /** \brief  Routine to call. */
+    void (*cb)(workqueue_t *queue, struct workqueue_job *job);
+
     /** \brief  List handle. No need to set manually. */
     STAILQ_ENTRY(workqueue_job) entry;
 } workqueue_job_t;