Allow empty layer lists like "," to select no layer.
Allow empty layer lists like "," to select no layer.

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