I was thinking that the following might be of any help.

I needed to add the following lines to the original spec file in order to successfully build:

%define kerbdir /usr/kerberos
(I don't know why Devrim's fixes did not work)

rm -rf autom4te.cache
(just before the autoconf command)

OS:
Red Hat Enterprise Linux AS release 3 (Taroon)
Linux 2.4.21-32.0.1.EL #1 Tue May 17 18:01:37 EDT 2005 i686 i686 i386 GNU/Linux

Packages:
rh-postgresql-server-7.3.10-2
rh-postgresql-7.3.10-2
rh-postgresql-devel-7.3.10-2
rh-postgresql-libs-7.3.10-2
autoconf-2.57-3
postgresql-slony1-engine-1.1.5-1_PG8.0.5.src.rpm (from http://pgfoundry.org/frs/?group_id=1000122)


Regards,
Viorel