tools: avoid OpenSSL deprecation warnings

Our Gitlab CI buildsystem is set up to treat warnings as errors.
With OpenSSL 3.0 a lot of deprecation warnings occur.

With the patch compatibility with OpenSSL 1.1.1 is declared.
In the long run we should upgrade our code to use the current API.

A -Wdiscarded-qualifiers warning is muted by casting.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

lib/aes/aes-encrypt.c

@@ -2,6 +2,9 @@
 /*
  * Copyright (c) 2019,Softathome
  */
+
+#define OPENSSL_API_COMPAT 0x10101000L
+
 #include "mkimage.h"
 #include <stdio.h>
 #include <string.h>