[kwin] Drop dead code

kwin_get_menu_pix_hack was no longer used anywhere.

client.cpp

@@ -43,7 +43,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #endif
 #include "workspace.h"
 // KDE
-#include <KDE/KIconLoader>
 #include <KDE/KWindowSystem>
 #include <KDE/KColorScheme>
 // Qt
@@ -2352,14 +2351,6 @@ void Client::debug(QDebug& stream) const
     print<QDebug>(stream);
 }
 
-QPixmap* kwin_get_menu_pix_hack()
-{
-    static QPixmap p;
-    if (p.isNull())
-        p = SmallIcon(QStringLiteral("bx2"));
-    return &p;
-}
-
 void Client::checkActivities()
 {
 #ifdef KWIN_BUILD_ACTIVITIES

tabbox/tabbox.cpp

@@ -63,8 +63,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 namespace KWin
 {
 
-extern QPixmap* kwin_get_menu_pix_hack();
-
 namespace TabBox
 {