[Pkg-kde-extras] Bug#1086765: kdiagram FTBFS with nocheck

[Rebecca N. Palmer]

Control: tags -1 patch

This looks similar to kimap #1086766: nocheck turns off BUILD_TESTING, 
and this package ships some items that are only built with that on. 
(nocheck is not allowed to change the contents of a package.)  The 
upstream code even notes (at src/KGantt/CMakeLists.txt:15) that they 
don't like this either.

Fix (two merge requests because this bug exists in both unstable and 
experimental):
https://salsa.debian.org/qt-kde-team/extras/kdiagram/-/merge_requests/5
https://salsa.debian.org/qt-kde-team/extras/kdiagram/-/merge_requests/6