This change improves copy_file_range(), sendfile(), splice(), openpty(),
closefrom(), close_range(), fadvise() and posix_fadvise() in addition to
writing tests that confirm things like errno and seeking behavior across
platforms. We now less aggressively polyfill behavior with some of these
functions when the platform support isn't available. Please see:
https://justine.lol/cosmopolitan/functions.html
This change upgrades to the latest Chromium Zlib, fixes bugs in redbean,
and introduces better support for reverse proxies like Cloudflare. This
change improves the security of redbean and it's recommended that users
upgrade to the release that'll follow. This change also updates the docs
to clarify how to use the security tools redbean provides e.g. pledge(),
unveil(), and the MODE=asan builds which improve memory safety.
