WIP: fix shader_runner error reporting when vertex data included.
Geometry shaders: add a basic EndPrimitive() test.
shader_runner: Add missing newlines to error messages.

Certain shader error messages were missing newlines, leading to the
error message being concatenated on the same line with "PIGLIT:
{'result': 'fail' }".
!UPSTREAM: disable running "-auto" tests before window appears

Seems to be necessary to work around nVidia bugs.

TODO:
- Make an environmnet variable option for doing this.
!UPSTREAM: GL 3.1: test that core features are properly excluded from old GLSL versions.

TODO:
- Do I need a better commit message?
- Test on nVidia
!UPSTREAM: gs: Test all core inputs except gl_PrimitiveIDIn.

gl_PrimitiveIDIn will need more aggressive testing, so that will be
addressed in a separate patch.

TODO:
- Add core outputs (gl_ClipDistance, gl_PointSize, and gl_PrimitiveID already done)
gs: Test gl_PrimitiveIDIn
!UPSTREAM: Test core GS inputs on GLSL 1.50