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.

Log message:
s6 TLS tools don't use OpenSSL, but do need to know where to find CA
certs. Buildlink just enough OpenSSL to read SSLDIR, then install a new
s6-pkgsrc-cadir program that knows it. Bump PKGREVISION.

Log message:
Add --enable-absolute-paths, as these programs need to invoke each other
while often running in freshly cleared environments. Bump PKGREVISION.

While here, make TLS (via BearSSL) optional, still on by default.

Log message:
Initial import of s6-networking, a suite of small networking tools for
Unix systems. It includes command-line client and server management, TCP
access control, privilege escalation across UNIX domain sockets, IDENT
protocol management, clock synchronization, and secure connections using
the TLS protocol.