Now I tried again with updated mesa (git-8ed6b14). Now glxgears, sauerbraten,
ut2004 (32bit), fgfs (when did 3d clouds become such a performance killer?) are
fine. Neverball still flashes garbage. Nexuiz is 3fps with AA. Etqw (32bit) and
team fortress 2 (32bit, wine) cause gpu lockup even without AA (I'll bisect
later). Alien-arena with AA dies with
r600_texture.c:776:r600_texture_transfer_map: Assertion
`rtex->resource.b.b.nr_samples <= 1' failed.

In all cases I had to use the env var, even games that support setting AA
cannot do it themselves.