Fix cmake variable

CMakeLists.txt

@@ -223,10 +223,10 @@ endif()
 
 check_include_files(unistd.h HAVE_UNISTD_H)
 
-if (IS_ABSOLUTE "${DBUS_INTERFACES_INSTALL_DIR}")
-    set(AKONADI_DBUS_INTERFACES_INSTALL_DIR "${DBUS_INTERFACES_INSTALL_DIR}")
+if (IS_ABSOLUTE "${KDE_INSTALL_DBUSINTERFACEDIR}")
+    set(AKONADI_DBUS_INTERFACES_INSTALL_DIR "${KDE_INSTALL_DBUSINTERFACEDIR}")
 else()
-    set(AKONADI_DBUS_INTERFACES_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/${DBUS_INTERFACES_INSTALL_DIR}")
+    set(AKONADI_DBUS_INTERFACES_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/${KDE_INSTALL_DBUSINTERFACEDIR}")
 endif()
 
 if (IS_ABSOLUTE "${KDE_INSTALL_INCLUDEDIR_KF}")