This patch modifies the transform feedback tessellation test to check
that the queries GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN and
GL_PRIMITIVES_GENERATED count the correct number of primitives for all
primitive types.  Previously, we were only testing correct behavior of
GL_TRANSFORM_FEEDBACK_PRIMITIVES and GL_PRIMITIVES_GENERATED in the
"position" test, which always draws triangles.

Verified that these tests still pass on the nVidia proprietary Linux
driver.

v2: Add GL_PRIMITIVES_GENERATED too.

Reviewed-by: Eric Anholt <eric@anholt.net>