Ignore SIGIO which gets sent if queue gets full. Also other small fixes/cleanups.
Ignore SIGIO which gets sent if queue gets full. Also other small
fixes/cleanups.

--HG--
branch : HEAD

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