This isn't significantly shorter than the first pass, but it's easier to
read and maintain. To add a new platform to this (if anyone wants to do
that), just add sane default paths to ACBuild-default.properties, add a
conditional to detect your platform, and add an init-platform target
that does the configuration.
There's a bit cleaner solution in ant-contrib using the if task, but
that means adding to the dependencies and therefore the complexity of
building this thing. I'm disinclined to do that.
Previously AC built onm Windows or not Windows (assumed to be Mac).
It appears there was a means to build using gcj, but this is not
necessary, does not work anymore as configured, and isn't what we want
anyway.
Here's a first pass at improving that situation. It's a bit ugly at
present because it requires a lot of markup to do something that should
be simple. Still, I'd rather do this in steps.
