Support using a statically linked lua from a subproject
Unfortunately I am stuck with only lua-5.1 widely available in my distro, thus I haven't been able to enable lua-factory in my grilo-plugins package (I'm the co-maintainer). There would be a lot of work to do outside my field to finally get 5.3 or newer universally available, so realistically I don't have the cycles to do that on my end (and apparently my peers neither still for years).
Thus I'm requesting that maybe grilo-plugins could bundle a lua copy as a subproject and support falling back to that (and lua upstream appears adamant about that approach too - static linking to some concrete version). I believe there's something available at https://github.com/mesonbuild/lua/ for this, but I'm not quite sure how those things are supposed to work.
This way my distro users would be able to use the lua factory plugins without having to wait for system-wide newer lua anymore, which appears particularly important for gnome-music use cases.