Merge branch 'jk/pack-idx-corruption-safety'

The code to read the pack data using the offsets stored in the pack idx file has been made more carefully check the validity of the data in the idx. * jk/pack-idx-corruption-safety: sha1_file.c: mark strings for translation use_pack: handle signed off_t overflow nth_packed_object_offset: bounds-check extended offset t5313: test bounds-checks of corrupted/malicious pack/idx files