[cairo] Optimize spans in the trapezoid rasterizer

[Billy Biggs]

Jeff Muizelaar (jeff at infidigm.net):

> On Sun, Jul 24, 2005 at 10:14:49PM -0500, Billy Biggs wrote:
> > If accepted, this patch should probably also get applied to the copy
> > in Xorg.
> 
> Does the patch apply cleanly to code in xserver/fb? It would be better
> if it went there first as that is considered the upstream for
> libpixman.  If applied there it will eventually make its way into
> libpixman as I finish the merging. However, if it applies cleanly to
> both xserver/fb and libpixman then it can probably be applied to
> libpixman right away, instead of waiting for it to come through
> merging. 

  The patch applies cleanly to both, which is one reason I decided to
start with this part of the code.  It's a lot easier to work with the
libpixman code since I can test it without building an X server.  :)
I do intend to touch this code again if my scanline optimization works
out.

  -Billy