Add MBEDTLS_ALLOW_PRIVATE_ACCESS to test programs

Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 1ff27fb..f7a424a 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -17,6 +17,8 @@
  *  limitations under the License.
  */
 
+#define MBEDTLS_ALLOW_PRIVATE_ACCESS
+
 #include "ssl_test_lib.h"
 
 #if defined(MBEDTLS_SSL_TEST_IMPOSSIBLE)