parse: set invalid group on option with no group set

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/parse.c b/parse.c
index 927f78b..606c54b 100644
--- a/parse.c
+++ b/parse.c
@@ -1171,6 +1171,7 @@
 	if (!o->category) {
 		log_info("Options %s: no category defined. Setting to misc\n", o->name);
 		o->category = FIO_OPT_C_GENERAL;
+		o->group = FIO_OPT_G_INVALID;
 	}
 	if (o->type == FIO_OPT_STR || o->type == FIO_OPT_STR_STORE ||
 	    o->type == FIO_OPT_STR_MULTI)