Log Message:
Update to 1.3.9. Fixes pkg/15568.
* maildrop/filter.C (xfilter): Set O_NDELAY on file descriptors for
  xfilter() since select() only works correctly on non-blocking fds.
* maildrop/formatmbox.C (GetFromLine): Do not write a newline before
  every From_ line...
* maildrop/deliver.C (delivery): ... only for 2nd and subsequent msgs.
* rfc2047.c (rfc2047_encode_callback): Fix MIME-encoding of spaces.
* rfc822.c (rfc822_prname_orlist): Dequote quoted-strings.
* rfc2045/reformime: Fix handling of unencoded nulls in text/plain
  content.
* rfc2045/reformime.sgml: Documented the -m and -D options.
* userdb/configure.in: Fix typo.
* rfc2045/rfc2045.c (doline): Fix incorrect calculation of the
  end of a multipart MIME section that's inside another multipart
  MIME section.
* maildir/maildirfiltertypelist.h: Fix typo.