gallium: remove use of origin_lower_left

This was used to indicate OpenGL's lower-left origin for fragment window
coordinates for polygon stipple and gl_FragCoord.

Now:
  - fragment coordinate origin is always upper-left corner
  - GL polygon stipple is inverted and shifted before given to gallium
  - GL fragment programs that use INPUT[WPOS] are modified to use an
    inverted window coord which is placed in a temp register.

Note: the origin_lower_left field still exists in pipe_rasterizer_state.
Remove it when all the drivers, etc. no longer reference it.

src/mesa/state_tracker/st_atom_rasterizer.c

@@ -79,6 +79,7 @@ static void update_raster_state( struct st_context *st )
 
    memset(raster, 0, sizeof(*raster));
 
+   /* XXX obsolete field, remove someday */
    raster->origin_lower_left = 1; /* Always true for OpenGL */
    
    /* _NEW_POLYGON, _NEW_BUFFERS