[Exim] make install funniness

This was totally my fault, but I thought I'd point it out anyway. I was
developing on one system which had a certain library installed, and tried
to 'make install' on a server which didn't have the libraries. I ended up
w/ the binary installed as "exim-" since the install script couldn't
figure out the build and version:

./exim: error while loading shared libraries: libbmiclient_single.so.1: cannot open shared object file: No such file or directory
cp exim /local/exim/bin/exim-
chown root /local/exim/bin/exim-
chmod a+x /local/exim/bin/exim-
chmod u+s /local/exim/bin/exim-

--John