Compatibility with Apache 2.4.
--- src/mod_dnssd.c.orig	2009-01-27 20:24:00.000000000 -0600
+++ src/mod_dnssd.c	2021-07-27 14:25:47.000000000 -0500
@@ -26,6 +26,7 @@
 #include <unixd.h>
 #include <apr_signal.h>
 #include <mpm_common.h>
+#include <mod_unixd.h>
 
 #include <unistd.h>
 
@@ -576,7 +577,7 @@
 
     ap_assert(d);
 
-    unixd_setup_child();
+    ap_unixd_setup_child();
 
     if (pipe(sigterm_pipe_fds) < 0) {
         ap_log_error(APLOG_MARK, APLOG_ERR, 0, r.main_server, "pipe() failed: %s", strerror(errno));