MINOR: queue: store a pointer to the queue into the pendconn

By following the queue pointer in the pendconn it will now be possible
to always retrieve the elements (index, srv, px, etc).
diff --git a/include/haproxy/queue-t.h b/include/haproxy/queue-t.h
index cb317db..a2e321c 100644
--- a/include/haproxy/queue-t.h
+++ b/include/haproxy/queue-t.h
@@ -28,11 +28,13 @@
 struct proxy;
 struct server;
 struct stream;
+struct queue;
 
 struct pendconn {
 	int            strm_flags; /* stream flags */
 	unsigned int   queue_idx;  /* value of proxy/server queue_idx at time of enqueue */
 	struct stream *strm;
+	struct queue  *queue;      /* the queue the entry is queued into */
 	struct proxy  *px;
 	struct server *srv;        /* the server we are waiting for, may be NULL if don't care */
 	struct server *target;     /* the server that was assigned, = srv except if srv==NULL */
diff --git a/src/queue.c b/src/queue.c
index f0dcd11..f84ec94 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -434,6 +434,7 @@
 		max_ptr = &px->be_counters.nbpend_max;
 	}
 
+	p->queue = q;
 	p->queue_idx  = _HA_ATOMIC_LOAD(&q->idx) - 1; // for logging only
 	new_max = _HA_ATOMIC_ADD_FETCH(&q->length, 1);
 	old_max = _HA_ATOMIC_LOAD(max_ptr);