From 111799ec94758be0567ef22b34097744df64c142 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Thu, 21 Mar 2013 11:43:51 -0600
Subject: [PATCH] Mac OS X: use IPV6_V6ONLY

As of 10.8, Mac OS X seems to behave more like Linux in the way
that IPv6 and IPv4 binding interact.

Closes PR 13193
---
 src/racket/sconfig.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/racket/sconfig.h b/src/racket/sconfig.h
index e90093295d..f0bba06980 100644
--- a/src/racket/sconfig.h
+++ b/src/racket/sconfig.h
@@ -756,6 +756,8 @@
 
 # define SIGSET_IS_SIGNAL
 
+# define MZ_TCP_LISTEN_IPV6_ONLY_SOCKOPT
+
 # define USE_TM_GMTOFF_FIELD
 # define USE_TM_ZONE_FIELD