Create compile script for Exim4

Exim4 is a well known MTA. We need a compile script that works both in Ubuntu 8.10 and Debian 5 (they're rather similar) that builds Exim4 from source and generates binaries that are equivalent to Debian's light daemon version. Probably you can just find out the build options used by Debian and use them in the current Exim4 (the packages in Ubuntu 8.10 in particular don't include DKIM which we need, this is why we need to compile from source and use the last versions). That's all. We don't need config, etc - just a clean build scripts that gives us a light exim4 (but with DKIM support) in those aging OS versions.