[Nouveau] Possible composition bug - please test

[Clemens Eisserer]

Hello,

I think I've stumbled over a composition bug (doesn't happen with
ExaNoComposite) which is also present in the Intel-Driver:
https://bugs.freedesktop.org/show_bug.cgi?id=16913

However the latest nouveau release I tested against was 0.10 (that one
shipped with Fedora9), and I don't have a spare system arround that I
could use for testing.

It would be really great if somebody running a more recent release
could try the source attached to the intel-bug-report, compile it
using:
gcc -lX11 -lXrender scale_clip_artifact2.c -o scale_clip_artifact
and just run it.

Thank you in advance and thanks for working on this really excellent
driver, Clemens