Changes to the auto builders

The Precise based hard float auto builders are now online. Every merge request and commit to gcc-linaro will now be built build both on a Natty softfp system and a Precise hard float. Let's run this in parallel for a while before updating the validation lab.

I've also updated the x86 cloud builders from Natty to Precise. A quick test showed no regressions but I want to run them in parallel for a bit to be sure.

-- Michael