https://github.com/curl/curl/commit/ae75db3527461248b0a7b1686df52200d28d83b9

From ae75db3527461248b0a7b1686df52200d28d83b9 Mon Sep 17 00:00:00 2001
From: annalee <150648636+a-n-n-a-l-e-e@users.noreply.github.com>
Date: Fri, 29 Dec 2023 05:43:33 +0000
Subject: [PATCH] configure: fix no default int compile error in ipv6 detection

Closes #12607
--- a/configure.ac
+++ b/configure.ac
@@ -1655,15 +1655,12 @@ AS_HELP_STRING([--disable-ipv6],[Disable IPv6 support]),
 # include <netinet/in6.h>
 #endif
 #endif
-#include <stdlib.h> /* for exit() */
-main()
+
+int main(void)
 {
  struct sockaddr_in6 s;
  (void)s;
- if (socket(AF_INET6, SOCK_STREAM, 0) < 0)
-   exit(1);
- else
-   exit(0);
+ return socket(AF_INET6, SOCK_STREAM, 0) < 0;
 }
 ]])
 ],