luabind depends either on lua or on luajit

Add new configuration option LUA, which
can be "lua" or "luajit" (by default, "lua").

This option is used currently only by package luabind.
Previously package luabind depended on lua.
Luabind built with Lua (5.2 for MXE) is
not binary compatible with LuaJIT (which is
binary compatible to Lua 5.1, not Lua 5.2).
That is why an application using luabind is to use
lua instead of luabind.

Currently the problem is solved.
Compile luabind against luajit:

    $ make luabind LUA=luajit

and link your application against luajit andluabind.

To compile luabind against Lua (previous and currently
default behaviour):

    $ make luabind LUA=lua

or just

    $ make luabind

http://permalink.gmane.org/gmane.comp.gnu.mingw.cross-env/3691