mesa: Change args to vbo_count_tessellated_primitives.

mesa: Change args to vbo_count_tessellated_primitives.

No functional change--this simply paves the way to allow futures
patches to call vbo_count_tessellated_primitives() during error
checking, before the _mesa_prim struct has been constructed.

This will be needed for GLES3, which requires draw calls to fail if
there is not enough space available in transform feedback buffers to
accommodate the primitives to be drawn.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Brian Paul <brianp@vmware.com>