configure: add -std=gnu99 to CFLAGS
configure: add -std=gnu99 to CFLAGS

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