draw: don't set the clipped window coordinate to NaN in debug

Setting the old window coordinate to NaN is more likely to hide the
problem in debug builds because the NaN vertices are dropped later in
the pipeline, either through explicit NaN checks or implicit line
length checks.

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Roland Scheidegger <roland.scheidegger@broadcom.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36653>

src/gallium/auxiliary/draw/draw_cliptest_tmp.h

@@ -181,17 +181,6 @@ TAG(do_cliptest)(struct pt_post_vs *pvs,
          position[2] = position[2] * w * scale[2] + trans[2];
          position[3] = w;
       }
-#if MESA_DEBUG
-      /* For debug builds, set the clipped vertex's window coordinate
-       * to NaN to help catch potential errors later.
-       */
-      else {
-         position[0] =
-         position[1] =
-         position[2] =
-         position[3] = NAN;
-      }
-#endif
 
       if ((flags & DO_EDGEFLAG) && ef) {
          const float *edgeflag = out->data[ef];