This fixes some tests with ARB shaders that were broken since
1360af6a. When buffer_internal_preload
is called by context_update_stream_info, si->elements[i].data is not yet
set.

Status items are the things on the right end of the Mac menu bar, like the
clock and volume widget.  It turns out that they are displayed at a higher
window level than everything else in the menu bar.  For the case where the
displays are not captured for a full-screen window, the window ends up at the
same window level as the status items, and they would sometimes end up on top.
They would draw over the full-screen window and could be clicked.

This was probably taken from the YUV shaders, incorrectly and in reverse
logic. It did happen to work though because fragment.texcoord[0].w is 1.0.