Support system and vendored Lua libraries

[terrablue]

Hey, I'm using your ziglua project to devendor lua in my redis fork. However, the vendored lua exposes two additional functions that it seems upstream doesn't otherwise expose (https://github.com/terrablue/zkv/blob/master/deps/lua/src/lua.h#L361-L362).

Would you mind exposing those functions as well? I find it very convenient to use ziglua as a dependency instead of rolling out my own.