trivial: Add some protection in asb_glob_value_search()
trivial: Split out asb_utils_sanitise_path() as a helper
Fix extraction of hardlinks

Do two passes of the file to extract: the first to find filenames that match
the glob, symlinks and any hardlinks; then the second to actually decompress
the files found in the hash.

This ensures we create the target of the hardlink before the hardlink itself.