Log Message:
Update "fetchmail" and "fetchmailconf" packages to version 6.3.8.
Changes since version 6.3.6:
- Make the APOP challenge parser more distrustful and have it reject
  challenges that do not conform to RFC-822 msg-id format, in the hope
  to make mounting man-in-the-middle attacks (MITM) against APOP a bit
  more difficult. (CVE-2007-1558)
- Fix pluralization of oversized-message warning mails.
- Fix manual page: --sslcheck -> --sslcertck, and do not set trailing
  "recommended:" in bold.
- Repoll immediately if a protocol error happens during the authentication
  attempt after a failed opportunistic TLS upgrade.
- Fix rendering of the "24 - 26, 28, 29" paragraph in the exit codes
  section.
- If SOCKS support was compiled in, add 'socks' to the feature_options
  Python list emitted in --configdump.
- Do not crash with a null pointer dereference when opening the BSMTP file
  fails. Improve error checking and reporting.
- Make BSMTP output actually work, it would persistently fail with SOCKET
  error after writing the first header.
- Fix KPOP.
- Fix repoll when server disconnects after opportunistic TLS failed for
  POP3.