attempt to silence Visual Studio warning about fopen()

Author: Cyan4973

tests/fullbench.c

@@ -16,6 +16,7 @@
 #define ZSTD_DISABLE_DEPRECATE_WARNINGS /* No deprecation warnings, we still bench some deprecated functions */
 #include "util.h"        /* Compiler options, UTIL_GetFileSize */
 #include <stdlib.h>      /* malloc */
+#define _CRT_SECURE_NO_WARNINGS /* disable Visual warning that it doesn't like fopen() */
 #include <stdio.h>       /* fprintf, fopen, ftello64 */
 #include <assert.h>