BUG/MINOR: stream-int: set SI_FL_WANT_PUT in sess_establish()

In commit f26c26c ("BUG/MEDIUM: stream-int: change the way buffer room
is requested by a stream-int") we used to call si_want_put() at the
end of sess_update_st_con_tcp(), when switching to SI_ST_EST state.
But this is incorrect as there are a few other situations where we
can switch to this state, such as in si_connect() where a connection
reuse is detected, or when directly calling an applet (in which case
that was already covered anyway). For now it doesn't have any side
effect but it could impact connection reuse after the stream-int
changes by stalling an immediately reused connection.

Let's move this flag change to sess_establish() instead, which is the
only place which is always called exactly once on connection setup.

No backport is needed, this is purely 1.9.
1 file changed