Rename frame_create and frame_set_child_size with a window_ prefix

This is to avoid a collision with an actual frame structure.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/clients/desktop-shell.c b/clients/desktop-shell.c
index 599c0a5..8c97104 100644
--- a/clients/desktop-shell.c
+++ b/clients/desktop-shell.c
@@ -896,7 +896,7 @@
 	dialog = xzalloc(sizeof *dialog);
 
 	dialog->window = window_create_custom(display);
-	dialog->widget = frame_create(dialog->window, dialog);
+	dialog->widget = window_frame_create(dialog->window, dialog);
 	window_set_title(dialog->window, "Unlock your desktop");
 
 	window_set_user_data(dialog->window, dialog);