Log Message:
Update to 2.4.0.0. From the changelog:

- Can be built against OpenSSL + libretls.
- execline is now optional.
- s6-tlsc and s6-tlsd rewrite. They're now wrappers around new
  binaries: s6-tlsc-io and s6-tlsd-io, which establish and run a
  TLS tunnel over already existing fds.
- New functionality: s6-ucspitlsc and s6-ucspitlsd, for an
  implementation of delayed encryption.

pkgsrc changes:

- Switch from BearSSL to LibreTLS (atop OpenSSL).
- Turn 'execline' option off by default.