Merge branch 'jk/pack-header-parse-alignment-fix'

It was possible for "git unpack-objects" and "git index-pack" to make an unaligned access, which has been corrected. * jk/pack-header-parse-alignment-fix: index-pack, unpack-objects: use skip_prefix to avoid magic number index-pack, unpack-objects: use get_be32() for reading pack header parse_pack_header_option(): avoid unaligned memory writes packfile: factor out --pack_header argument parsing bswap.h: squelch potential sparse -Wcast-truncate warnings