[monitoring-plugins] users.c: Include default definitions

[Lorenz Kästle]

 Module: monitoring-plugins
 Branch: master
 Commit: ee3c903fbe37cc5c7537921cdb31e39b4ea25bc6
 Author: Lorenz Kästle <12514511+RincewindsHat at users.noreply.github.com>
   Date: Wed Mar 12 22:06:54 2025 +0100
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=ee3c903f

users.c: Include default definitions

---

 plugins/check_users.d/users.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/plugins/check_users.d/users.c b/plugins/check_users.d/users.c
index 7969ae79..95c05d6f 100644
--- a/plugins/check_users.d/users.c
+++ b/plugins/check_users.d/users.c
@@ -50,6 +50,7 @@ get_num_of_users_wrapper get_num_of_users_windows() {
 #else // _WIN32
 
 #	include "../../config.h"
+#	include <stddef.h>
 
 #	ifdef HAVE_LIBSYSTEMD
 #		include <systemd/sd-daemon.h>