GnuTLS todo item about using an equivalent of `SSL_peak()`, which
nicely escaped the word checks, is no longer relevant.
We do not use `SSL_peek()` anymore since connection filters were
introduced.
Closes #14091
13.16 Share the CA cache
13.17 Add missing features to TLS backends
- 14. GnuTLS
- 14.2 check connection
-
15. Schannel
15.1 Extend support for client certificate authentication
15.2 Extend support for the --ciphers option
features are supported by which TLS backends, and thus also where there are
feature gaps.
-14. GnuTLS
-
-14.2 check connection
-
- Add a way to check if the connection seems to be alive, to correspond to the
- SSL_peak() way we use with OpenSSL.
-
15. Schannel
15.1 Extend support for client certificate authentication