Log Message:
Update "stunnel" package to version 4.56. Changes since 4.55:
- Fixed a regression bug introduced in version 4.55 causing random
  crashes on several platforms, including Windows 7.
- Fixed incorrect "stunnel -exit" process synchronisation.
- Fixed FIPS detection with new versions of the OpenSSL library.
- Failure to open the log file at startup is no longer ignored.