Stop rewriting symlinks

[victorb]

Currently because of https://github.com/ipfs/go-ipfs/pull/3508, when we finished pulling down the arch mirror, we are rewriting all the symlinks with their targets, effectively doubling the size of the arch-repository on disk. This is not a big issue since when we add it to IPFS, de-duplication takes care of the sizing and we end up with good size again.

When symlinks are handled by go-ipfs, we can remove this step.

[NiKiZe]

I'm looking to do something similar with Gentoo-distfiles and symlinks is an issue that we kind of need a fix for. However in the mean time you might be able to create hard links instead, which would not take up more space, so ln -f "$abstarget" "$link" should work instead (rm should not be needed)

or use cp -l which does the hard linking