ah ha! - you're running 10.0.4! there's been a major change in ld under 10.1 (5g15, 5g48, and 5g64) that breaks postgres... postgresql 7.1.3 built fine for me under 10.0.4 too
it also seems that using a binary of postgresql 7.1.3 (I found a bunch out there) break under 10.1 as well... I'm...
well - 10.1 & postgresql & fink aren't ready yet - maybe soon... there's also an issue with initdb when you don't build postgresql as shared libraries - I haven't looked into it enough yet to figure out why
see...