ok, reinstalled now some packages from macports without x11 support (hoping that it uses quartz instead):
sudo port install cairo -x11 +quartz gtk2 +no_x11 +quartz pango +no_x11 +quartz gtksourceview2 +quartz gtkglext +quartz libsdl +no_x11
(based on people reporting similar problems:
http://lists.gnu.org/archive/html/linphone-developers/2012-12/msg00053.html)
ufoai compiles, but when I want to start it it complains:
------- video initialization -------
Video SDL_Init failed: No available video device
so that's not working. I will now try to install an older version of the libsdl, as it seems that recently there have been made some changes (see
http://trac.macports.org/ticket/37562).
let's see how that works out...