Log Message:
Update mail/dovecot2-pigeonhole to 0.5.0.

* editheader extension: The implementation of header modifications is
  heavily updated. Although the functionality has not changed, the
  underlying code was updated to address several static analysis
  warnings, runtime integer arithmetic warnings (Clang), and to match
  updates in the Dovecot stream API.
+ variables extension: Made the maximum scope and variable size
  configurable.
+ subaddress: Support multiple recipient_delimiters.
- enotify extension: mailto method: Fixed parsing of mailto URI with
  only a header part.
- enotify plugin: mailto method: Make sure the "From:" header is set to
  a usable address and not "(null)".
- Fixed writing address headers to outgoing messages. Sometimes headers
  were MIME-encoded twice, yielding invalid results.