CMake: Make usage of LUA_PATH in LuaJITAddExecutable depend on it being set

[squeek502]

Should fix #242

Let me know if this'll work for you @carlocab

[carlocab]

I believe this should work, but let me test it out later.

One thing I'm confused about: the CMake variable LUA_PATH is populated by the environment variable LUA_PATH. luajit should already be reading LUA_PATH from the environment and using that value when it's set, so it seems redundant to me to have to call luajit with LUA_PATH=....

What am I missing here?

[squeek502]

I'm also unclear on that, but wanted to leave it alone just in case. Here's where it was added: #122

[zhaozg]

I have not ideas about this. Maybe found we need find more direct way.

[carlocab]

Thanks @squeek502!

[zhaozg]

My mistake

I found the similarly problem, when I do coveralls test lua-openssl. [here]https://github.com/zhaozg/lua-openssl/runs/4824775420?check_suite_focus=true#step:5:599

This maybe a bug in ubuntu with apt install luajit libluajit-5.1-dev, https://github.com/zhaozg/lua-openssl/actions/runs/1700632752/workflow#L19

After build luajit from git source, this issue disappeared.