rebase zip64 local-header offset in zip_entries_delete_mark

[jmestwa-coder]

zip_entries_delete_mark rebases the wrong offset field for a zip64 entry:

• after a delete shifts an entry data it rewrites the raw 32-bit central-directory offset field
• a zip64 entry holds 0xFFFFFFFF there and keeps the real offset in an extra field, so the subtract turns the sentinel into 0xFFFFFFFF - deleted_length and leaves the extra field stale, and the survivor can no longer be located (read fails)
• zip_cdh_set_local_offset now writes the resolved offset into the zip64 extra field for such entries and the 32-bit field otherwise

repro: craft a zip64 archive, delete a preceding entry, read the survivor back. test_entries_delete_zip64_offset fails on master and passes here.