Fix crash in shutdown of /dev/mem system.
Fix crash in shutdown of /dev/mem system.

djbclark/directfb-core-DirectFB,lancebaiyouview/DirectFB,sklnet/DirectFB,djbclark/directfb-core-DirectFB,kevleyski/directfb,Distrotech/DirectFB,sklnet/DirectFB,mtsekm/test,deniskropp/DirectFB,mtsekm/test,kevleyski/DirectFB-1,mtsekm/test,kaostao/directfb,kevleyski/DirectFB-1,kevleyski/DirectFB-1,DirectFB/directfb,djbclark/directfb-core-DirectFB,DirectFB/directfb,DirectFB/directfb,jcdubois/DirectFB,Distrotech/DirectFB,kevleyski/directfb,dfbdok/DirectFB1,dfbdok/DirectFB1,lancebaiyouview/DirectFB,kevleyski/directfb,sklnet/DirectFB,lancebaiyouview/DirectFB,kaostao/directfb,deniskropp/DirectFB,kevleyski/directfb,kevleyski/DirectFB-1,jcdubois/DirectFB,deniskropp/DirectFB,Distrotech/DirectFB,kaostao/directfb,djbclark/directfb-core-DirectFB,jcdubois/DirectFB,deniskropp/DirectFB,dfbdok/DirectFB1,sklnet/DirectFB,lancebaiyouview/DirectFB