Util: Add dfb_regions_unite() to calculate bounds of one or more regions.
Util: Add dfb_regions_unite() to calculate bounds of one or more regions.

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