Fix additional libarchive comment typos

[gshaowei6]

Summary:

• Fix several spelling mistakes in libarchive comments which are not covered by Fix cosmetic typos #683.
• Keep the changes limited to comments; no generated files or behavior are changed.

Tests:

• codespell libarchive/archive_entry_stat.c libarchive/archive_util.c libarchive/archive_windows.c
• git diff --cached --check before publishing

Related to #684.

[gperciva]

Thanks for the attention, but we are deliberately not making cosmetic changes to libarchive code, to minimize diffs to libarchive upstream.

I made some of those fixes to https://github.com/libarchive/libarchive/ a few years ago; please send any further fixes for libarchive code to them.

[gshaowei6]

Thanks for clarifying the maintenance policy. I will close this PR rather than keeping a cosmetic libarchive-vendored diff open in Tarsnap.

If I pursue these remaining typo fixes, I will send them to libarchive/libarchive instead, where this code is maintained upstream.