[tex-k] texmfcnf.lua is outdated and breaks ConTeXt.

[Karl Berry]

    Arch Linux includes its own patched version of texmfcnf.lua on
    https://github.com/archlinux/svntogit-packages/commit/43af7cc2eab080ea4f333159833e714376cb2cad

Looks to me like those changes are arch-specific, hardwiring /etc/ and
so on.

    It's been broken for years.

After installing a new vanilla TL (from upstream, not any distro's
version) with collection-context, mtxrun --generate apparently worked
fine. Also, I modify and retypeset a ConTeXt document every year (the
pdftex manual), and it has worked.  --best, karl.