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/editor.c b/clients/editor.c
index 32c3f9b..0de2500 100644
--- a/clients/editor.c
+++ b/clients/editor.c
@@ -1056,7 +1056,7 @@
 	g_type_init();
 #endif
 
-	editor.display = display_create(argc, argv);
+	editor.display = display_create(&argc, argv);
 	if (editor.display == NULL) {
 		fprintf(stderr, "failed to create display: %m\n");
 		return -1;