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/clickdot.c b/clients/clickdot.c
index c74bc91..714b4b9 100644
--- a/clients/clickdot.c
+++ b/clients/clickdot.c
@@ -297,7 +297,7 @@
 	struct display *display;
 	struct clickdot *clickdot;
 
-	display = display_create(argc, argv);
+	display = display_create(&argc, argv);
 	if (display == NULL) {
 		fprintf(stderr, "failed to create display: %m\n");
 		return -1;