Having a look at
<http://www-
03.ibm.com/systems/power/software/aix/linux/toolbox/alpha.html>

gcc libffi is wel available for Aix, though?

That said, I just need python for bzr and associated tools to maintain 
localy a small number of script, so imho I would be able survive 
without ffi support in python (even _ctype?).

Any idea how to remove this support at build from src time: I have a 
look at ./configure --help and even try to change some other 
compilation option like -O2 (in place of default -O3) but nothing 
seems to be helpfull.

Tx for additional advise.