I'm getting the exact same compiler error with 1.1.5 as here:
http://gborg.postgresql.org/pipermail/slony1-general/2007-January/005678.html

<<confoptions.c:115: undefined reference to `pg_qsort'>>

I tried the suggested fix there and got the same negative result as
the original poster.

Any suggestions to get 1.1.5 to compile? I don't want to upgrade the
version of Slony on the existing servers.

I'm using FreeBSD 6.1 and Postgres 8.2.4.

- Don Barthel