If error message from PAM was over ~500 bytes, we crashed. Probably never happened. Also use PIPE_BUF instead of hardcoded 512 bytes.
If error message from PAM was over ~500 bytes, we crashed. Probably never
happened. Also use PIPE_BUF instead of hardcoded 512 bytes.

--HG--
branch : HEAD

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