[Piglit] [PATCH v2 0/6] gs: Test interaction between geometry shaders and transform feedback counting.

[Paul Berry]

Minor fixes based on review feedback from Ian:

- Misplaced hunks from patch 6 moved to patches 1 and 4.

- Patches 3 and 5 will use VAO's when GL version >= 3.0.

- In patch 6's geometry shader, make positions array const, and fix
  outer loop bound.

[PATCH v2 1/6] Add PIGLIT_STRIP_ARG() macro for extracting args during piglit config.
[PATCH v2 2/6] Use PIGLIT_STRIP_ARG() in formats.c
[PATCH v2 3/6] Support both core and compat contexts in xfb/overflow-edge-cases.c.
[PATCH v2 4/6] gs: Adapt xfb/overflow-edge-cases.c for geometry shaders.
[PATCH v2 5/6] Support both core and compat contexts in xfb/intervening-read.c.
[PATCH v2 6/6] gs: Adapt xfb/intervening-read.c for geometry shaders.