Merged upstream as https://github.com/pyca/```
security/py-cryptography/pull/6360 and backported to this version.: Add LibreSSL 3.4.0 support
While here, remove remaining FreeBSD 11 cruftBackport upstream #6360 [1]
Approved by: While here, remove remaining FreeBSD 11 support
[1] https://github.com/pyca/cryptography/pull/6360
Reviewed_by: koobs (maintainer), ??
Approved by: ?? (mentor), koobs (maintainer, implicit?))
Differential_Revision: D32281
MFH: 2020Q4 (blanket: build fix)
```