Bug#989011: ksudoku FTBFS on armhf in buster

[Adrian Bunk <bunk@debian.org>]

Source: ksudoku
Version: 4:18.04.1-1
Severity: serious
Tags: ftbfs
Control: fixed -1 4:20.04.2-2

https://tests.reproducible-builds.org/debian/rb-pkg/buster/armhf/ksudoku.html

...
In file included from /usr/include/arm-linux-gnueabihf/qt5/QtCore/qglobal.h:50,
                 from /usr/include/arm-linux-gnueabihf/qt5/QtCore/qnamespace.h:43,
                 from /usr/include/arm-linux-gnueabihf/qt5/QtCore/qobjectdefs.h:48,
                 from /usr/include/arm-linux-gnueabihf/qt5/QtCore/qobject.h:46,
                 from /usr/include/arm-linux-gnueabihf/qt5/QtCore/QObject:1,
                 from /build/ksudoku-18.04.1/src/gui/ksudokugame.h:26,
                 from /build/ksudoku-18.04.1/src/gui/views/ksview.h:26,
                 from /build/ksudoku-18.04.1/src/gui/views/ksview.cpp:23:
/usr/include/assert.h:92: note: this is the location of the previous definition
 #  define assert(expr)       \
 
In file included from /build/ksudoku-18.04.1/src/gui/views/roxdokuview.h:34,
                 from /build/ksudoku-18.04.1/src/gui/views/ksview.cpp:35:
/build/ksudoku-18.04.1/src/gui/views/ArcBall.h:44:10: fatal error: GL/glu.h: No such file or directory
 #include <GL/glu.h>                                                                                            // Header File For The GLu32 Library
          ^~~~~~~~~~
compilation terminated.
make[4]: *** [src/gui/CMakeFiles/ksudoku_gui.dir/build.make:212: src/gui/CMakeFiles/ksudoku_gui.dir/views/ksview.cpp.o] Error 1