fix Windows nightly. windows.h and opengl.h needs to be included before everything
Should fix https://binary-factory.kde.org/view/Windows%2064-bit/job/KSudoku_Nightly_win64/399/console
(locally tested)
Should fix https://binary-factory.kde.org/view/Windows%2064-bit/job/KSudoku_Nightly_win64/399/console
(locally tested)