[Piglit] GL_LIGHTING test

[Michal Suchanek]

Hello

I experience issues with some 3D applications rendering odd (too
bright) on a r600.

Going through mesa demos I noticed that GL_LIGHTING produces different
result on r600 than other cards making the bright area larger.

I wrote a test that checks for this difference.

For me it fails on r600, r600g and llvmpipe and succeeds on swrast. It
should also succeed on r300 or i915 which render the demo much like
swrast but I did not actually run the test on them.

The test can be found at
http://repo.or.cz/w/piglit/hramrach.git/shortlog/refs/heads/wip

I would like to get a test for this issue into piglit so that it's
easy to check.

If the test is inadequate please specify how it should be improved.

Thanks

Michal