[Intel-gfx] i965 fs shader debugging

[Ben Widawsky]

These are the mesa patches that go with the patches that I posted to
intel-gfx for intel-gpu-tools:
<1308080767-21176-1-git-send-email-ben at bwidawsk.net> which begin to
allow HW supported shader debugging on Gen6 and above.

I'll send out a big patch series with all the components when ready, but
I can start taking feedback on these now.

Thanks.
Ben