BUG/MAJOR: stream: Force channel analysis on successful synchronous send

BUG/MAJOR: stream: Force channel analysis on successful synchronous send

This patchs reverts commit a498e527b ("BUG/MAJOR: stream: Remove READ/WRITE
events on channels after analysers eval") because of a regression. It was an
attempt to properly detect synchronous sends, even when the stream was woken
up on a write event. However, the fix was wrong because it could mask
shutdowns performed during process_stream() and block the stream.

Indeed, when a shutdown is performed, because an error occurred for
instance, a write event is reported. The commit above could mask this event
while the shutdown prevent any synchronous sends. In such case, the stream
could remain blocked infinitly because an I/O event was missed.

So to properly fix the original issue (#3070), the write event must not be
masked before a synchronous send. Instead, we now force the channel analysis
by setting explicitly CF_WAKE_ONCE flags on the corresponding channel if a
write event is reported after the synchronous send. CF_WRITE_EVENT flag is
remove explicitly just before, so it is quite easy to detect.

This patch must be backport to all stable version in same time of the commit
above.