lib: connection: Now uses io_add_istream() instead of io_add().
lib: connection: Now uses io_add_istream() instead of io_add().

LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot