MINOR: protocol: replace ->pause(listener) with ->rx_suspend(receiver)

The ->pause method is inappropriate since it doesn't exactly "pause" a
listener but rather temporarily disables it so that it's not visible at
all to let another process take its place. The term "suspend" is more
suitable, since the "pause" is actually what we'll need to apply to the
FULL and LIMITED states which really need to make a pause in the accept
process. And it goes well with the use of the "resume" function that
will also need to be made per-protocol.

Let's rename the function and make it act on the receiver since it's
already what it essentially does, hence the prefix "_rx" to make it
more explicit.

The protocol struct was a bit reordered because it was becoming a real
mess between the parts related to the listeners and those for the
receivers.
diff --git a/src/proto_uxst.c b/src/proto_uxst.c
index 2610927..7278d51 100644
--- a/src/proto_uxst.c
+++ b/src/proto_uxst.c
@@ -43,7 +43,7 @@
 static int uxst_bind_listener(struct listener *listener, char *errmsg, int errlen);
 static int uxst_connect_server(struct connection *conn, int flags);
 static void uxst_add_listener(struct listener *listener, int port);
-static int uxst_pause_listener(struct listener *l);
+static int uxst_suspend_receiver(struct receiver *rx);
 
 /* Note: must not be declared <const> as its list will be overwritten */
 static struct protocol proto_unix = {
@@ -53,11 +53,11 @@
 	.sock_domain = PF_UNIX,
 	.sock_type = SOCK_STREAM,
 	.sock_prot = 0,
+	.add = uxst_add_listener,
+	.listen = uxst_bind_listener,
+	.rx_suspend = uxst_suspend_receiver,
 	.accept = &listener_accept,
 	.connect = &uxst_connect_server,
-	.listen = uxst_bind_listener,
-	.pause = uxst_pause_listener,
-	.add = uxst_add_listener,
 	.receivers = LIST_HEAD_INIT(proto_unix.receivers),
 	.nb_receivers = 0,
 };
@@ -146,15 +146,17 @@
 	proto_unix.nb_receivers++;
 }
 
-/* Pause a listener. Returns < 0 in case of failure, 0 if the listener
- * was totally stopped, or > 0 if correctly paused. Nothing is done for
+/* Suspend a receiver. Returns < 0 in case of failure, 0 if the receiver
+ * was totally stopped, or > 0 if correctly suspended. Nothing is done for
  * plain unix sockets since currently it's the new process which handles
  * the renaming. Abstract sockets are completely unbound and closed so
  * there's no need to stop the poller.
  */
-static int uxst_pause_listener(struct listener *l)
+static int uxst_suspend_receiver(struct receiver *rx)
 {
-	if (((struct sockaddr_un *)&l->rx.addr)->sun_path[0])
+	struct listener *l = LIST_ELEM(rx, struct listener *, rx);
+
+	if (((struct sockaddr_un *)&rx->addr)->sun_path[0])
 		return 1;
 
 	/* Listener's lock already held. Call lockless version of