Fix ci break in builds without platform.h
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 2eff043..6d4438d 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -13,6 +13,8 @@
 #define mbedtls_fprintf    fprintf
 #define mbedtls_printf     printf
 #define mbedtls_snprintf   snprintf
+#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
+#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
 #endif
 
 #if defined(MBEDTLS_MEMORY_BUFFER_ALLOC_C)