Support MoonJIT as a LuaJIT successor

[XVilka]

Since Mike Pall stepped down in LuaJIT development, project largely stalled. Soon, number of forks appeared, but the most promising one is MoonJIT. They strive to keep the compatibility, but also add a newer Lua (5.2, 5.3) features. Also they work hard on adding more platforms for JIT compilation.

https://github.com/moonjit/moonjit

Some Linux distributions already use some patches from the MoonJIT in their LuaJIT packages, e.g. Fedora and Debian.

[stuartwang]

Thanks for suggestion. We will do compatibility test for MoonJIT when support Luajit.