Log Message:
Update sylpheed package to 3.1.1.
Patch was provided by PR pkg/45088 from ISIHARA Takanori.

Changes of Sylpheed

* 3.1.1 (stable)

    * The column width of the address book will be saved now.
    * The keyboard shortcut of 'File/Send' menu of compose window was changed
      to prevent accidental sending.
    * The bug that caused occasional crash when summary was updated while
      receiving messages was fixed.
    * The compilation problem on some environment was fixed.
    * Some locale problems on Mac OS X was fixed.
    * The compilation error on newer gcc was fixed.
    * Finnish translation was added.