SSL test programs: allow for test hooks init and error reports

Create utility functions to set up test hooks and report errors that
the test hooks might detect. Call them in ssl_client2 and ssl_server2.

Test hooks are potentially enabled by compiling with
MBEDTLS_TEST_HOOKS.

This commit only sets up the functions. It doesn't make them do
anything yet.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

programs/ssl/ssl_test_lib.c

@@ -321,4 +321,21 @@ int idle( mbedtls_net_context *fd,
     return( 0 );
 }
 
+#if defined(MBEDTLS_TEST_HOOKS)
+
+void test_hooks_init( void )
+{
+}
+
+int test_hooks_failure_detected( void )
+{
+    return( 0 );
+}
+
+void test_hooks_free( void )
+{
+}
+
+#endif /* MBEDTLS_TEST_HOOKS */
+
 #endif /* !defined(MBEDTLS_SSL_TEST_IMPOSSIBLE) */