BUG/MEDIUM: checks: immediately report a connection success

BUG/MEDIUM: checks: immediately report a connection success

When no check type is configured (so the basic connection check), we
want the connection success to be immediately reported. Unfortunately,
it did not happen because in this case the connection is not registered
for read nor for write, and the wake_srv() callback does not handle this
case where no data transfer was requested. However, having option tcp-check
hides this problem because the check type follows a different setup mode,
by having check->type != 0 and the connection believing it must try to
send data.

The effect was that without any option, checks would succeed only at the
end of the check interval. So let's just add the wake-up condition.

This bug appeared with the recent polling changes, no backport is needed.
As a workaround, using "option tcp-check" fixes the problem.