[SDL] SDL displaying wrong colors with DirectX and windowed 8bpp mode

[Ryan C. Gordon]

> Neither SDL_HWPALETTE nor SDL_SWPALETTE.

Set SDL_HWPALETTE, then.

But really, something like Qemu, which wants to write to the framebuffer 
directly all the time, shouldn't be using HWSURFACE. On Linux/X11 and 
windib, HWSURFACE is ignored, so they probably never noticed an issue, 
but it's probably seriously hurting performance on DirectX, which has to 
keep moving the screen surface back and forth over the bus.

I still think either adding HWPALETTE or removing HWSURFACE should 
probably fix the color problem, though.

--ryan.