Revert "use wrapper to set LUA_PATH variable"

This reverts commit 807cd4b4, as it
broke the 'awesome' package. It was also an incomplete change, only
modifying lua-5.1 and none of the other lua versions.

A better approach, if wanting lua to pick up external modules, would be
to loop over $NIX_PROFILES. $NIX_PROFILES is unset in build
environments, so it should be safe.

Conflicts:
	pkgs/development/interpreters/lua-5/5.1.nix