extract_archive: use copy_pathname instead of set_pathname.
extract_archive: use copy_pathname instead of set_pathname.

Libarchive documentation mentions that archive_entry_set_pathname
expects us to keep the passed string alive, which we don't.

rycee/nix,NixOS/nix,rycee/nix,rycee/nix,NixOS/nix,rycee/nix,NixOS/nix,NixOS/nix,NixOS/nix,rycee/nix