Use kdeqt5staging for QCommandLineParser

Makes it also compile with not latest Qt.

CMakeLists.txt

@@ -231,6 +231,7 @@ set(kwin_QT_LIBS
 set(kwin_KDE_LIBS
     ${KDE4Support_LIBRARIES}
     ${KDECLARATIVE_LIBRARIES}
+    kdeqt5staging # TODO: remove once QCommandLineParser is dropped
     KF5::KConfigCore
     KF5::KCoreAddons
     KF5::KCrash

killer/CMakeLists.txt

@@ -13,6 +13,7 @@ target_link_libraries(kwin_killer_helper
     KF5::KAuth
     KF5::KI18n
     KF5::KWidgetsAddons
+    kdeqt5staging # TODO: remove once QCommandLineParser is dropped
 )
 
 install(TARGETS kwin_killer_helper DESTINATION ${LIBEXEC_INSTALL_DIR} )

killer/killer.cpp

@@ -26,7 +26,7 @@ DEALINGS IN THE SOFTWARE.
 #include <KDE/KLocalizedString>
 #include <KDE/KAuth/Action>
 #include <QApplication>
-#include <QCommandLineParser>
+#include <qcommandlineparser.h>
 #include <QDebug>
 #include <QProcess>
 #include <QtX11Extras/QX11Info>

main.cpp

@@ -43,7 +43,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // Qt
 #include <qplatformdefs.h>
 #include <QComboBox>
-#include <QCommandLineParser>
+#include <qcommandlineparser.h>
 #include <QDialog>
 #include <QDialogButtonBox>
 #include <QLabel>