Linking with -objc solved that, but now I got a warning:
/usr/bin/ld: warning: libobjc.so.lf2, needed by /usr/lib/gcc/powerpc-linux-gnu/4.1.3/../../../../lib/libFoundation.so, may conflict with libobjc.so.1
Perhaps this can be fixed by removing the dependency on libFoundation?
Also, running the program does not work:
You must call +[NSProcessInfo initializeWithArguments:count:environment:] in main()
(Again this is caused by libFoundation, I think.)