[layers] Fixed failing context lock assertion in dfb_wm_close_stack() by locking in context destructor.
[layers] Fixed failing context lock assertion in dfb_wm_close_stack() by locking in context destructor.

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