Update vendor/libarchive to git c31379acc9009f5a3bafcfa33d7672a24b3f51f3
Vendor issues fixed (FreeBSD):
PR #778: ACL error handling
Issue #745: Symlink check prefix optimization is too aggressive
Issue #746: Hard links with data can evade sandboxing restrictions
This update fixes the vulnerability #3 and vulnerability #4 as reported in
the "non-cryptanalytic attacks against FreeBSD update components".
https://gist.github.com/anonymous/e48209b03f1dd9625a992717e7b89c4f
Vulnerability #2 has already been fixed in r304866