Continue the size_t evacuation. fast-import's helper
gfi_unpack_entry() and the five size-handling sites that feed off
it (store_object()'s deltalen, load_tree(), parse_from_existing(),
the inline gfi_unpack_entry() caller in parse_objectish(),
cat_blob(), and dereference()) all carry size_t-shaped values from
the odb / unpack_entry() APIs through cast_size_t_to_ulong()
bridges into unsigned long locals.
With the producers (odb_read_object(), odb_read_object_peeled(),
unpack_entry()) and the consumers it feeds (the zlib avail_in
field from a prior commit, encode_in_pack_object_header()'s
uintmax_t parameter, parse_from_commit()'s widened size parameter)
all size_t-ready, the bridges and casts go away in one pass.
gfi_unpack_entry() now writes into the caller's size_t directly,
and the six locals collapse to plain size_t declarations.
Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
e9aa08fde6