MINOR: listener: move the INHERITED flag down to the receiver

It's the receiver's FD that's inherited from the parent process, not
the listener's so the flag must move to the receiver so that appropriate
actions can be taken.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 84b3635..fe0fdca 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -777,7 +777,7 @@
 	          thread_mask(listener->rx.settings->bind_thread) & all_threads_mask);
 
 	/* for now, all regularly bound TCP listeners are exportable */
-	if (!(listener->options & LI_O_INHERITED))
+	if (!(listener->rx.flags & RX_F_INHERITED))
 		fdtab[fd].exported = 1;
 
  tcp_return: