OpenSSL: Allow two server certificates/keys to be configured on server

OpenSSL: Allow two server certificates/keys to be configured on server

hostapd EAP server can now be configured with two separate server
certificates/keys to enable parallel operations using both RSA and ECC
public keys. The server will pick which one to use based on the client
preferences for the cipher suite (in the TLS ClientHello message). It
should be noted that number of deployed EAP peer implementations do not
filter out the cipher suite list based on their local configuration and
as such, configuration of alternative types of certificates on the
server may result in interoperability issues.

Signed-off-by: Jouni Malinen <j@w1.fi>