[lltx] Luatex and multiple pattern files

[Arthur Reutenauer]

  Claudio is trying to extend gloss-latin.ldf, so telling him that the
file -- which he wrote himself -- currently works well is not very
helpful ;-)

  Claudio, please describe precisely what the new option is expected to
do, I'll help you write the code.  Better yet, open an issue on the
GitHub tracker: https://github.com/reutenauer/polyglossia/issues/ so
that the discussion takes place in the proper location.

	Best,

		Arthur