security/openvpn-devel: upgrade port to git commit 9f4670fc71 (2025-02-12)

Contains a number of bugfixes and minor improvements, especially adding
more unit tests and cleaning up code all over the place.

The most important new feature in here is the "epoch data format",
which is a suitable data channel format & rekeying strategy for 10G+
links where regular AES rekeying starts to become a limiting factor.

When using FreeBSD DCO, epoch data format is not yet being used, because
this needs kernel changes in ovpn(4). This is on the roadmap.

• Additional edits by mandree@: --

reset PORTREVISION

PR: 284766