addition of necessary but forgotten cast

Author: czurnieden

bn_mp_to_radix.c

@@ -66,7 +66,7 @@ mp_err mp_to_radix(const mp_int *a, char *str, size_t *maxlen, int radix)
    /* append a NULL so the string is properly terminated */
    *str = '\0';
    digs++;
-   *maxlen = digs;
+   *maxlen = (size_t)digs;
 
 LBL_ERR:
    mp_clear(&t);