config/conf.pl starts with '#!/usr/bin/perl', so it
will run only on sites which have perl in /usr/bin.
Some have it in /usr/local/bin, on some it's in even weirder places.
The following trick fixes that, using /usr/bin/env (which is available on all Unices I know of) to
find perl in the environment, and invoke it:
#! /usr/bin/env perl
# Invoke perl without making assumptions about
# its location