REORG: listener: create a new struct receiver

In order to start to split the listeners into the listener part and the
event receiver part, we introduce a new field "rx" into struct listener
that will eventually become a separate struct receiver. This patch only
adds the struct with an options field that the receivers will need.

include/haproxy/listener-t.h

@@ -191,6 +191,11 @@ struct bind_conf {
 	} settings;                /* all the settings needed for the listening socket */
 };
 
+/* This describes a receiver with all its characteristics (address, status, etc) */
+struct receiver {
+	unsigned int flags;             /* receiver options (RX_F_*) */
+};
+
 /* The listener will be directly referenced by the fdtab[] which holds its
  * socket. The listener provides the protocol-specific accept() function to
  * the fdtab.
@@ -229,6 +234,7 @@ struct listener {
 	struct list by_bind;            /* chaining in bind_conf's list of listeners */
 	struct bind_conf *bind_conf;	/* "bind" line settings, include SSL settings among other things */
 	struct list proto_list;         /* list in the protocol header */
+	struct receiver rx;             /* network receiver parts */
 
 	/* warning: this struct is huge, keep it at the bottom */
 	struct sockaddr_storage addr;	/* the address we listen to */