The only animal in the buildfarm running AIX is grebe
(http://buildfarm.postgresql.org/cgi-bin/show_history.pl?nm=grebe&br=HEAD)
It is likely that the server running this animal will go away sometime
this year and the machine replacing it isn't running AIX.
If someone else in the community is running PostgreSQL on AIX then it
would be good if they setup a buildfarm member, perhaps with a more
recent version of AIX.
Steve