allow system luabins

[guijan]

trafficstars

Pulled out of #225. It shouldn't have been in that PR because it's unrelated.

[CoffeeFlux]

I'm hesitant to merge this until I can figure out what the local version is and whether it has any changes. I don't know why it was initially vendored.

[guijan]

luabins is abandoned https://github.com/agladysh/luabins (repository archived) and Aegisub already has fixes on the vendored source code: https://github.com/TypesettingTools/Aegisub/commit/8d8ea166df71e148a54a5a396c2faa44ec87779c

Package maintainers can create a luabins package from Aegisub's source tree though.

[kasper93]

Package maintainers can create a luabins package from Aegisub's source tree though.

This is convoluted way to develop a package... in subproject directory. If this luabins should be packages it should be forked as TypesettingTools/luabins with proper release with the needed changes.

[arch1t3cht]

Closing this for now for the above reasons. If official luabins packages ever appear in distros, this can be revisited.

The long-term plan is to phase out luabins anyway, see #382.