Fix macros in benchmark.c
#2124 may suffer from the same problem.
diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index 74fcaa6..b005c20 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -31,11 +31,7 @@
#include <stdlib.h>
#define mbedtls_exit exit
#define mbedtls_printf printf
-#define mbedtls_snprintf snprintf
#define mbedtls_free free
-#define mbedtls_exit exit
-#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
-#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
#endif
#if !defined(MBEDTLS_TIMING_C)