Util: Remove assertion from unimplemented dfb_clear_depth().
Util: Remove assertion from unimplemented dfb_clear_depth().

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