[Mesa-dev] New VS by default.

[Eric Anholt]

With the core GLSL fixups I just sent out plus this patch series, I
think it's ready to turn on by default.  piglit is non-regressing, and
the oglconform I've tested is overall better (but not perfect), and I
think it will fix one actual bug report.

Performance is likely to be lower on some applications (I'd be
interested in knowing which) until the optimization patches land.