Created attachment 9677 fix-gtimeval-deprecation.diff Untested.
Andre Miranda referenced this bugreport in commit fa8ca40cebc6ab37dd550c1e9b6e557a9f871f71 Fix GTimeVal deprecation (Bug #16643) https://git.xfce.org/xfce/xfce4-panel/commit?id=fa8ca40cebc6ab37dd550c1e9b6e557a9f871f71
Tested. Thanks for the patch! :)