MAJOR: stream: Use SE descriptor date to detect read/write timeouts

MAJOR: stream: Use SE descriptor date to detect read/write timeouts

We stop to use the channel's expiration dates to detect read and write
timeouts on the channels. We now rely on the stream-endpoint descriptor to
do so. All the stuff is handled in process_stream().

The stream relies on 2 helper functions to know if the receives or sends may
expire: sc_rcv_may_expire() and sc_snd_may_expire().