Pass the wqueue directly to the wqueue callback functions

src/wqueue.c

@@ -15,7 +15,7 @@ static int uc_wqueue_handle_write(struct UCWQueue *wqueue)
         q = UC_TAILQ_FIRST(&wqueue->queue);
 
         mbuf = UC_TAILQ_CONTAINER(q, struct MBuf, entry);
-        rc = wqueue->write_cb(mux, fd, mbuf);
+        rc = wqueue->write_cb(mux, wqueue, mbuf);
         if (rc <= 0) {
             //NOTE for rc < 0, nothing can touch the wqueue or fd
             //any more, as it might been free'd
@@ -58,7 +58,7 @@ static void uc_wqueue_cb(struct IOMux *mux, struct IOMuxFD *fd, unsigned int wha
 
 
     if (rc >= 0 && what & MUX_EV_READ) {
-        rc = wqueue->read_cb(mux, fd);
+        rc = wqueue->read_cb(mux, wqueue);
         //NOTE - can't touch the wqueue or fd after this point,
         //as it might been free'd
     }