vbo: Implement new gs prim types in vbo_count_tessellated_primitives.
!UPSTREAM: WIP: vbo: Make vbo_sw_primitive_restart optionally count primitives.

This will be necessary in order to get the i965 back-end to produce
the correct value of gl_PrimitiveIDIn when using primitive restart.
!UPSTREAM: WIP: i965/gs: Fix gl_PrimitiveIDIn when using SW primitive restart.

TODO:
- Write the front-end portion.  At the moment nobody is setting brw->prim_restart.sw_prim_counter.