Fix forgotten snprintf define for MSVC
diff --git a/programs/test/benchmark.c b/programs/test/benchmark.c
index c7f7f82..3c1bc0a 100644
--- a/programs/test/benchmark.c
+++ b/programs/test/benchmark.c
@@ -49,6 +49,10 @@
 #include "polarssl/ecdsa.h"
 #include "polarssl/ecdh.h"
 
+#if defined _MSC_VER && !defined snprintf
+#define snprintf _snprintf
+#endif
+
 #define BUFSIZE         1024
 #define HEADER_FORMAT   "  %-16s :  "
 #define TITLE_LEN       17