mmap(MAP_FIXED) may return ENOMEM as well as EINVAL if address+length isn't valid. Also some other cleanups.
mmap(MAP_FIXED) may return ENOMEM as well as EINVAL if address+length
isn't valid. Also some other cleanups.

--HG--
branch : HEAD

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