guards ticket creation field

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index a152a30..9365c62 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1248,7 +1248,9 @@
     uint8_t MBEDTLS_PRIVATE(ticket_flags);      /*!< Ticket flags */
     uint32_t MBEDTLS_PRIVATE(ticket_age_add);               /*!< Randomly generated value used to obscure the age of the ticket */
     uint8_t MBEDTLS_PRIVATE(resumption_key_len);            /*!< resumption_key length */
+#if defined(MBEDTLS_HAVE_TIME)
     mbedtls_ms_time_t MBEDTLS_PRIVATE(ticket_creation);     /*!< create time of ticket */
+#endif
     unsigned char MBEDTLS_PRIVATE(resumption_key)[MBEDTLS_SSL_TLS1_3_TICKET_RESUMPTION_KEY_LEN];
 
 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) && defined(MBEDTLS_SSL_CLI_C)