security/openconnect: update to 9.12

[diizzy]

Upstream log suggests that we should use latest release (9.12) and I would also recommend to replace ftp with https since it's being deprecated.

https://www.infradead.org/openconnect/changelog.html
https://www.infradead.org/openconnect/download/ --> https://www.infradead.org/openconnect/download/openconnect-9.12.tar.gz

Austin, did you do any testing in Poudriere and/or runtime testing, if so what version(s) and platform(s)?

[ashafer]

Updated to 9.12, switched to https, fixed a warning about requiring
libp11-kit that make stage-qa threw.

I've done runtime testing with connecting to a VPN (on CURRENT). I
haven't done any poudriere testing, but if you have a suggestion I can.