security/openvpn-devel: switch to Gitlab and new maintainer

The previous maintainer asked that the port be removed, but
we seem to have found a better solution. Gert Doering volunteered
to take over the port and reference Git directly.

Import security/openvpn fix for leftover .orig files.

PR: 256209
Maintainer change implicitly
Approved by: ecrist@secure-computing.net (removal request)
New contents reviewed and
Approved by: gert@greenie.muc.de (new maintainer, by IRC/mail)