configure: Use O2 by default.
configure: Use O2 by default.

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