[cairo] turn off antialiasing

[mental at rydia.net]

Quoting DANIELLLANO <DANIELLLANO at terra.es>:

> None, that I know.
> But, Why would you like to turn antialiasing off?

High-resolution output.  If your output resolution is high enough,
things can look worse with antialiasing than without (e.g. due to
fringing).

Also, some applications like SVG renderers may find it desirable to
turn antialiasing off, as the standard includes means for
requesting this on a per-object basis.

-mental