Pass argc pointer to parse_options()

This lets us keep argc up to date as the backend picks out arguments
from the argv array.
diff --git a/clients/eventdemo.c b/clients/eventdemo.c
index e59b076..05ad5dc 100644
--- a/clients/eventdemo.c
+++ b/clients/eventdemo.c
@@ -390,11 +390,11 @@
 	struct display *d;
 	struct eventdemo *e;
 
-	argc = parse_options(eventdemo_options,
-			     ARRAY_LENGTH(eventdemo_options), argc, argv);
+	parse_options(eventdemo_options,
+		      ARRAY_LENGTH(eventdemo_options), &argc, argv);
 
 	/* Connect to the display and have the arguments parsed */
-	d = display_create(argc, argv);
+	d = display_create(&argc, argv);
 	if (d == NULL) {
 		fprintf(stderr, "failed to create display: %m\n");
 		return -1;