rigctld show-conf now exits only if no -r argument is given

https://github.com/Hamlib/Hamlib/issues/1619

tests/rigctld.c

@@ -761,8 +761,11 @@ int main(int argc, char *argv[])
     if (show_conf)
     {
         rig_token_foreach(my_rig, print_conf_list, (rig_ptr_t)my_rig);
-        fflush(stdout);
+        if (rig_file == NULL)
-        exit(0);
+        {
+            fflush(stdout);
+            exit(0);
+        }
     }
 
     /*