If you're running PG 7.2.x, you'll also need to make this change to your configure script:
1579,1580c1579,1580
< if test -f $PG_INSTALLATION_DIR/include/postgresql/postgres.h; then
< PG_INC="$PG_INSTALLATION_DIR/include/postgresql"
---
> if test -f $PG_INSTALLATION_DIR/include/server/postgres.h; then
> PG_INC="$PG_INSTALLATION_DIR/include/server"
Also, make sure you ran
make install-all-headers
when you installed PG.