https://github.com/fvwmorg/fvwm3/pull/914
From: Matt Jolly <Matt.Jolly@footclan.ninja>
Date: Tue, 17 Oct 2023 16:01:33 +1000
Subject: [PATCH] Fix implicit function declaration in configure

Missing unistd.h include for `close` and `unlink`
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -996,6 +996,7 @@ AC_DEFUN([AM_SAFETY_CHECK_MKSTEMP],[
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 int main(void)
 {
   char template[128];
-- 
2.42.0