[x11] Added missing check of layer pixel format based on conversion routines available.
[x11] Added missing check of layer pixel format based on conversion routines available.

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