tun-device: Remove the superfluous use of select() before read()

src/libstrongswan/networking/tun_device.h

@@ -31,8 +31,6 @@ typedef struct tun_device_t tun_device_t;
  * Class to create TUN devices
  *
  * Creating such a device requires the CAP_NET_ADMIN capability.
- *
- * @note The implementation is currently very Linux specific
  */
 struct tun_device_t {
 
@@ -42,7 +40,7 @@ struct tun_device_t {
 	 * @note This call blocks until a packet is available. It is a thread
 	 * cancellation point.
 	 *
-	 * @param packet		the packet read from the device
+	 * @param packet		the packet read from the device, allocated
 	 * @return				TRUE if successful
 	 */
 	bool (*read_packet)(tun_device_t *this, chunk_t *packet);