Support for Lua modules.

[Aleksey Cheusov <cheusov%tut.by@localhost>]

I'm packaging a few Lua (lang/lua) modules in WIP, e.g.
wip/lua-{stdlib,lrexlib-{onig,pcre,posix}}.

Current Lua version is 5.1 and modules should be installed
to lib/lua/5.1 directory, but it's not clear for me how
to detect this directory properly from modules' Makefile.

Probably lang/lua/module.mk should be created for this.
Has anybody any idea? Or maybe somebody can implement this.

lang/lua is assigned to pkgsrc-users@, so I'm asking here.

-- 
Best regards, Aleksey Cheusov.