I've seen several posts about this and contacted the developers
at Yellow Dog Linux. Turns out they have the same problem and the
only way they have gotten PostgreSQL to work is by compiling with
a -O0 flag.
My guess is there is some problem in gcc specific to the PowerPC
platform. I can get PostgreSQL to work either with the native xlc
compiler + -O2 or gcc + -O0.
Suggestions?