API: Remove totally unused and unneeded DSBLIT_SOURCE2.
API: Remove totally unused and unneeded DSBLIT_SOURCE2.

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