Stop exporting a sane PATH

Currently the script exports a "sane" PATH which causes trouble if there are conflicting utilities under one of those sane path directories (especially /usr/local/bin).

The issue I had was that the build process was failing because I had Rust uutils in /usr/local/bin, but being a diligent user I had removed it from the PATH and it was still failing. I was baffled and did not find out the issue until I had manually removed od from /usr/local/bin.

I highly recommend removing this archaic bandaid, mkinitcpio isn't supposed to be a rescue tool which works in a broken environment. If for some reason you (the developers) do not like doing this, at the very least please remove /usr/local/bin from this "sane" list! It is highly unsafe (maybe even insane) to source coreutils from the local user's bin directory.

Thank you in advance!