libffi tarballs for GHC

This repository contains the source tarballs used to build libffi for GHC. While in principle this repository should contain official source tarballs from the libffi project, the recent lack of releases has meant that we have had to start packaging our own snapshots.

Note that in order to reduce working tree size, this repository contains only orphan branches. Each branch contains one source tarball. These tarballs and their branches are generated using the mk-snapshot.sh script.

In order to update the libffi version built by GHC, first run mk-snapshot.sh, then push the resulting branch to git.haskell.org, and finally update the submodule commit in the ghc repository.