[Pixman] [PATCH pixman] V5 implement PIXMAN_FILTER_GOOD/BEST

[Bill Spitzak]

This is identical to my previous series of patches except rebased atop the 
current git master.

With all of these applied, the filter generation can be removed from cairo as 
pixman will do it. The fallback to image for the X11 backend could be removed 
if it is known the server is using this new version.

Output is nearly identical to what cairo is producing now, but I did some 
minor tweaks to cutoffs between filters and handling of very small scales. 
This one also detects a few more instances where nearest or bilinear can be 
used as a fast path.