iostream-ssl: Don't hang if ostream's max buffer size is set to 0.
iostream-ssl: Don't hang if ostream's max buffer size is set to 0.

jkerihuel/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot