[monitoring-plugins] Fix for -Wunused-but-set-variable

[RincewindsHat]

 Module: monitoring-plugins
 Branch: master
 Commit: 79e2f520942451a3651dbcfebd4672a02c52dcbf
 Author: RincewindsHat <12514511+RincewindsHat at users.noreply.github.com>
   Date: Mon Oct 16 00:59:30 2023 +0200
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=79e2f52

Fix for -Wunused-but-set-variable

---

 plugins-root/check_dhcp.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/plugins-root/check_dhcp.c b/plugins-root/check_dhcp.c
index 5ba9372..6b07df5 100644
--- a/plugins-root/check_dhcp.c
+++ b/plugins-root/check_dhcp.c
@@ -1064,12 +1064,10 @@ int get_results(void){
 
 /* process command-line arguments */
 int process_arguments(int argc, char **argv){
-	int arg_index;
-
 	if(argc<1)
 		return ERROR;
 
-	arg_index = call_getopt(argc,argv);
+	call_getopt(argc,argv);
 	return validate_arguments(argc);
 }