OPENSSL_buf2hexstr_ex
int OPENSSL_buf2hexstr_ex(char *str, size_t str_n, size_t *strlength,
&& TEST_false(OPENSSL_buf2hexstr_ex(out, 3 * len - 1, NULL, buf, len,
&& TEST_true(OPENSSL_buf2hexstr_ex(out, sizeof(out), NULL, buf, len,
&& TEST_true(OPENSSL_buf2hexstr_ex(out, sizeof(out), NULL, buf, 0,