vbo: Test for VBO_SAVE_PRIM_WEAK in _mesa_prim::mode is false.

When setting the _mesa_prim::mode field we always filter out
all non OpenGL primitive mode bits. So this tested bit cannot be
there anymore and the test evaluates to zero.
The zero is removed with the next patch to ease review.

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Mathias Fröhlich <Mathias.Froehlich@web.de>

src/mesa/vbo/vbo_save_loopback.c

@@ -227,7 +227,7 @@ _vbo_loopback_vertex_list(struct gl_context *ctx,
    const struct _mesa_prim *prims = node->prims;
    const GLuint prim_count = node->prim_count;
    for (GLuint i = 0; i < prim_count; i++) {
-      if ((prims[i].mode & VBO_SAVE_PRIM_WEAK) && _mesa_inside_begin_end(ctx)) {
+      if ((0) && _mesa_inside_begin_end(ctx)) {
          loopback_weak_prim(ctx, &prims[i]);
       } else {
          loopback_prim(ctx, buffer, &prims[i], wrap_count, stride, la, nr);