OpenSSL 3.0 in the base system update

As previously mentioned[1] FreeBSD 14.0 will include OpenSSL 3.0.  We
expect to merge the update to main in the near future (within the next
week or two) and are ready for wider testing.

Supported by the FreeBSD Foundation, Pierre Pronchery has been working
on the update in the src tree, with assistance from Enji Cooper
(ngie@), and me (emaste@). Thanks to Antoine Brodin (antoine@) and
Muhammad Moinur Rahman (bofh@) for ports exp-runs and
fixes/workarounds and to Dag-Erling (des@) for updating ldns in the
base system.

## Base system compatibility status

Most of the base system is ready for a seamless switch to OpenSSL 3.0.
For several components we've added `-DOPENSSL_API_COMPAT=0x10100000L`
to CFLAGS to specify the API version, which avoids deprecation
warnings from OpenSSL 3.0. Changes have also been made to avoid
OpenSSL APIs already deprecated in OpenSSL 1.1. We can continue the
process of updating to contemporary APIs after OpenSSL 3.0 is in the
tree.

Additional changes are still required for libarchive and seven
Kerberos-related libraries or tools. Workarounds are ready to go along
with the OpenSSL 3 import, and proper fixes are in progress in the
upstream projects.

A segfault from `openssl x509` in the i386 ports exp-run is under
investigation and needs to be addressed prior to the merge.

## Ports compatibility

With bofh@'s recent www/node18 and www/node20 patches the ports tree
is in reasonable shape for OpenSSL 3.0 in the base system. The exp-run
(link below) has a list of the failing ports, and I've emailed all of
the maintainers as a heads-up. None of the remaining failures are
responsible for a large number of skipped ports (i.e., the failures
are either leaf ports or are responsible for only a small number of
skipped ports). I expect that some or many of these will need to be
addressed after the change lands in the src tree.

## Call for testing

We welcome feedback from anyone willing to test the work in progress.
Pierre's update can be obtained from the pull request[2] or by
fetching the branch[3]. If desired I will provide a large diff against
main.

## Links

- Base system OpenSSL 3.0 update tracking PR:
  https://bugs.freebsd.org/271615

- Ports exp-run with OpenSSL 3.0 in the base system:
  https://bugs.freebsd.org/271656

[1] https://lists.freebsd.org/archives/freebsd-current/2023-May/003609.html
[2] https://github.com/freebsd/freebsd-src/pull/760
[3] https://github.com/khorben/freebsd-src/tree/khorben/openssl-3.0.9