Check PRF availability on initialisation and add --force-tls-key-material-export

Check PRF availability on initialisation and add --force-tls-key-material-export

We now warn a user if the TLS 1.0 PRF is not supported by the cryptographic
library of the system. Also add the option --force-tls-key-material-export
that automatically rejects clients that do not support TLS Keying Material
Export and automatically enable it when TLS 1.0 PRF support is not available.

Change-Id: I04f8c7c413e7cb62c726262feee6ca89c7e86c70
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20240104140214.32196-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg27924.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>