mesa: fix transform feedback when a geometry shader is active.

mesa: fix transform feedback when a geometry shader is active.

When a geometry shader is active, the transform feedback primitive
type ("mode") needs to be validated against the geometry shader output
primitive type, not the primitive type passed to the glDraw*()
function.

Fixes the following piglit tests:
- glsl-1.50-geometry-primitive-types GL_LINES
- glsl-1.50-geometry-primitive-types GL_LINES_ADJACENCY
- glsl-1.50-geometry-primitive-types GL_LINE_STRIP
- glsl-1.50-geometry-primitive-types GL_LINE_STRIP_ADJACENCY
- glsl-1.50-geometry-primitive-types GL_TRIANGLES
- glsl-1.50-geometry-primitive-types GL_TRIANGLES_ADJACENCY
- glsl-1.50-geometry-primitive-types GL_TRIANGLE_FAN

Exposes previously hidden failures in the following piglit tests:
- glsl-1.50-geometry-primitive-id-restart GL_LINES other
- glsl-1.50-geometry-primitive-id-restart GL_LINES_ADJACENCY other
- glsl-1.50-geometry-primitive-id-restart GL_LINE_LOOP ffs
- glsl-1.50-geometry-primitive-id-restart GL_LINE_LOOP other
- glsl-1.50-geometry-primitive-id-restart GL_LINE_STRIP other
- glsl-1.50-geometry-primitive-id-restart GL_LINE_STRIP_ADJACENCY other
- glsl-1.50-geometry-primitive-id-restart GL_TRIANGLES other
- glsl-1.50-geometry-primitive-id-restart GL_TRIANGLES_ADJACENCY other
- glsl-1.50-geometry-primitive-id-restart GL_TRIANGLE_FAN ffs
- glsl-1.50-geometry-primitive-id-restart GL_TRIANGLE_FAN other
- glsl-1.50-geometry-primitive-id-restart GL_TRIANGLE_STRIP other
- glsl-1.50-geometry-primitive-id-restart GL_TRIANGLE_STRIP_ADJACENCY other

(These failures were previously hidden due to a flaw in the test: it
doesn't check for GL errors.  I'll fix the test shortly).

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>