luajit: bump new version

Cleaned up the tests code according to the Lua style guide:
- made scoped variables local
- added os.exit call at the end of the test chunk
- adjusted the messages in test:ok calls

(cherry picked from commit 3c641629)

luajit @ cf847585

-Subproject commit c633004489e63ba182514558adfeb0507642d2c0
+Subproject commit cf8475858861d28d1ea6d4de15e146370b3a24f2