MINOR: queue: add a pointer to the server and the proxy in the queue

A queue is specific to a server or a proxy, so we don't need to place
this distinction inside all pendconns, it can be in the queue itself.
This commit adds the relevant fields "px" and "sv" into the struct
queue, and initializes them accordingly.
diff --git a/include/haproxy/queue-t.h b/include/haproxy/queue-t.h
index cbc9d71..cb317db 100644
--- a/include/haproxy/queue-t.h
+++ b/include/haproxy/queue-t.h
@@ -41,6 +41,8 @@
 
 struct queue {
 	struct eb_root head;                    /* queued pendconnds */
+	struct proxy  *px;                      /* the proxy we're waiting for, never NULL in queue */
+	struct server *sv;                      /* the server we are waiting for, may be NULL if don't care */
 	__decl_thread(HA_SPINLOCK_T lock);      /* for manipulations in the tree */
 	unsigned int idx;			/* current queuing index */
 	unsigned int length;                    /* number of entries */
diff --git a/include/haproxy/queue.h b/include/haproxy/queue.h
index 3e79507..8478965 100644
--- a/include/haproxy/queue.h
+++ b/include/haproxy/queue.h
@@ -109,11 +109,18 @@
 	return offset;
 }
 
-static inline void queue_init(struct queue *queue)
+/* initialize the queue <queue> for proxy <px> and server <sv>. A server's
+ * always has both a valid proxy and a valid server. A proxy's queue only
+ * has a valid proxy and NULL for the server queue. This is how they're
+ * distinguished during operations.
+ */
+static inline void queue_init(struct queue *queue, struct proxy *px, struct server *sv)
 {
 	queue->head = EB_ROOT;
 	queue->length = 0;
 	queue->idx = 0;
+	queue->px = px;
+	queue->sv = sv;
 	HA_SPIN_INIT(&queue->lock);
 }
 
diff --git a/src/proxy.c b/src/proxy.c
index 3c67950..764207d 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -1292,7 +1292,7 @@
 {
 	memset(p, 0, sizeof(struct proxy));
 	p->obj_type = OBJ_TYPE_PROXY;
-	queue_init(&p->queue);
+	queue_init(&p->queue, p, NULL);
 	LIST_INIT(&p->acl);
 	LIST_INIT(&p->http_req_rules);
 	LIST_INIT(&p->http_res_rules);
diff --git a/src/server.c b/src/server.c
index 95a479d..d63c3f1 100644
--- a/src/server.c
+++ b/src/server.c
@@ -2160,7 +2160,7 @@
 
 	srv->obj_type = OBJ_TYPE_SERVER;
 	srv->proxy = proxy;
-	queue_init(&srv->queue);
+	queue_init(&srv->queue, proxy, srv);
 	LIST_APPEND(&servers_list, &srv->global_list);
 	LIST_INIT(&srv->srv_rec_item);
 	LIST_INIT(&srv->ip_rec_item);