[Nouveau] texture layout test

[Hervé Cauwelier]

I come back on this matter because I was away when you posted it.

I read you've got enough feedback for NV86 cards but mine doesn't seem
to match your assumptions:

[...]
x 197 y 151
offset 38734 offset_expected 38478
x 198 y 151
offset 38735 offset_expected 38479
[...]

I didn't touch the source code, so it's in NV84_MODE.

The complete output is available at http://pastebin.ca/1364759

The other program nv9x_special "map fails", just for the completeness.

Hervé