MINOR: ssl: Add support for EC for the CA used to sign generated certificates

This is done by adding EVP_PKEY_EC type in supported types for the CA private
key when we get the message digest used to sign a generated X509 certificate.
So now, we support DSA, RSA and EC private keys.

And to be sure, when the type of the private key is not directly supported, we
get its default message digest using the function
'EVP_PKEY_get_default_digest_nid'.

We also use the key of the default certificate instead of generated it. So we
are sure to use the same key type instead of always using a RSA key.
diff --git a/include/proto/ssl_sock.h b/include/proto/ssl_sock.h
index b877580..24b4330 100644
--- a/include/proto/ssl_sock.h
+++ b/include/proto/ssl_sock.h
@@ -71,9 +71,9 @@
 int ssl_sock_load_global_dh_param_from_file(const char *filename);
 #endif
 
-SSL_CTX *ssl_sock_create_cert(const char *servername, unsigned int serial, X509 *cacert, EVP_PKEY *capkey);
-SSL_CTX *ssl_sock_get_generated_cert(unsigned int serial, X509 *cacert);
-int ssl_sock_set_generated_cert(SSL_CTX *ctx, unsigned int serial, X509 *cacert);
+SSL_CTX *ssl_sock_create_cert(struct connection *conn, const char *servername, unsigned int serial);
+SSL_CTX *ssl_sock_get_generated_cert(unsigned int serial, struct bind_conf *bind_conf);
+int ssl_sock_set_generated_cert(SSL_CTX *ctx, unsigned int serial, struct bind_conf *bind_conf);
 unsigned int ssl_sock_generated_cert_serial(const void *data, size_t len);
 
 #endif /* _PROTO_SSL_SOCK_H */