sysctl: reset 'r' only where needed

src/sysctl/sysctl.c

@@ -279,11 +279,11 @@ static int run(int argc, char *argv[]) {
         if (!sysctl_options)
                 return log_oom();
 
-        r = 0;
-
         if (argc > optind) {
                 int i;
 
+                r = 0;
+
                 for (i = optind; i < argc; i++) {
                         k = parse_file(sysctl_options, argv[i], false);
                         if (k < 0 && r == 0)