Warn about insecure ciphers also in init_key_type

Warn about insecure ciphers also in init_key_type

With modern Clients and server initialising the crypto cipher later
and not when reading in the config, most users never the warning when
having selected BF-CBC in the configuration.

This patch adds the logic to print out warning to init_key_type.

Main reason for this patch is a personal experience with someone who was
strictly against putting 'cipher' into a config file because he did not
like hardcoding a cipher and "OpenVPN will do AES-GCM anyway" and thinks
that it is better to not have it in configuration even after told by me
that 15 year defaults might not be good anymore.

Patch V2: rebase on master, fix minor style issues

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Steffan Karger <steffan.karger@foxcrypto.com>
Message-Id: <20200219112153.13013-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg19476.html
Signed-off-by: David Sommerseth <davids@openvpn.net>