build script for pcsx2

This script must be run on a 32 bit Linux environment.

I've uploaded a test version `0:1.2.1.0-testunpatched` which corresponds to our currently used version `1:1.2.2-4`

https://launchpad.net/~beauman/+archive/ubuntu/retrorig/+build/6258335

Just in case we need some source modifications...