Fix 64bit Mac OS X w/ LuaJIT.

On my 64bit Mac OS X 10.9 machine, starting CorsixTH fails when
`luaL_newstate()` returns NULL, printing:

  Fatal error starting CorsixTH: Cannot open Lua state.

It turns out that 64bit LuaJIT on Mac OS X requires special linker flags, from http://luajit.org/install.html :

    If you're building a 64 bit application on OSX which links directly or indirectly against LuaJIT, you need to link your main executable with these flags:
        -pagezero_size 10000 -image_base 100000000
Merge pull request #249 from jorgenpt/luajit-64bit-mac-fix

Fix 64bit Mac OS X w/ LuaJIT.