gallium: add point_quad_rasterization bit to rasterizer state

This determines if points should be rasterized according to GL point rules
or as normal quads (GL point sprites / d3d points / d3d point sprites).

src/gallium/drivers/svga/svga_pipe_rasterizer.c

@@ -72,6 +72,7 @@ svga_create_rasterizer_state(struct pipe_context *pipe,
    /* poly_smooth            - XXX: no fallback available */
    /* poly_stipple_enable    - draw module */
    /* sprite_coord_enable    - ? */
+   /* point_quad_rasterization - ? */
    /* point_size_per_vertex  - ? */
    /* sprite_coord_mode      - ??? */
    /* bypass_vs_viewport_and_clip        - handled by viewport setup */