MEDIUM: listener: Bind listeners on a thread subset if specified

If a "process" option with a thread set is used on the bind line, we use the
corresponding bitmask when the listener's FD is created.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 5badda7..606c3c5 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -1107,7 +1107,10 @@
 
 	fdtab[fd].owner = listener; /* reference the listener instead of a task */
 	fdtab[fd].iocb = listener->proto->accept;
-	fd_insert(fd, MAX_THREADS_MASK);
+	if (listener->bind_conf->bind_thread[relative_pid-1])
+		fd_insert(fd, listener->bind_conf->bind_thread[relative_pid-1]);
+	else
+		fd_insert(fd, MAX_THREADS_MASK);
 
  tcp_return:
 	if (msg && errlen) {