I tried to build postgres 7.3.4-r1 without ant, and the configure stage died complaining that ant didn't work. 7.4 does not have this problem. Perhaps ant needs to be a dependency?
Postgres ppl: latest stable is 7.4.6, 7.3.4-r1 isn't even in the archive anymore. Can you please close this if it is indeed not a problem anymore?
Closing, please reopen if you still have the same issue with versions that actually are in portage now. Sorry for zero response from pqsql herd. :/