Add SSL presets.

No need to use a separate profile as in X.509, everything we need is already
in ssl_config. Just load appropriate values.
diff --git a/programs/ssl/ssl_mail_client.c b/programs/ssl/ssl_mail_client.c
index 9587b7a..c06d0c0 100644
--- a/programs/ssl/ssl_mail_client.c
+++ b/programs/ssl/ssl_mail_client.c
@@ -587,7 +587,8 @@
 
     if( ( ret = mbedtls_ssl_config_defaults( &conf,
                     MBEDTLS_SSL_IS_CLIENT,
-                    MBEDTLS_SSL_TRANSPORT_STREAM ) ) != 0 )
+                    MBEDTLS_SSL_TRANSPORT_STREAM,
+                    MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
     {
         mbedtls_printf( " failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret );
         goto exit;