MINOR: protocols: always pass a "port" argument to the listener creation

It's a shame that cfgparse() has to make special cases of each protocol
just to cast the port to the target address family. Let's pass the port
in argument to the function. The unix listener simply ignores it.
diff --git a/include/proto/proto_uxst.h b/include/proto/proto_uxst.h
index d7bcaa6..63de24f 100644
--- a/include/proto/proto_uxst.h
+++ b/include/proto/proto_uxst.h
@@ -26,7 +26,7 @@
 #include <types/stream.h>
 #include <types/task.h>
 
-void uxst_add_listener(struct listener *listener);
+void uxst_add_listener(struct listener *listener, int port);
 int uxst_pause_listener(struct listener *l);
 int uxst_get_src(int fd, struct sockaddr *sa, socklen_t salen, int dir);
 int uxst_get_dst(int fd, struct sockaddr *sa, socklen_t salen, int dir);