gallium: remove use of origin_lower_left

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.