[cairo] Making Cairo friendlier for embedded use

[Ben Roe]

> I was wondering if anyone has been considering the long-term impact of
> the floating point intensive Cairo on embedded products wishing to
> make use of Gtk+?

IIRC from when I tested Cairo on ARM a while back, the performance
increase from replacing the trigonometric functions with fixed-point
table-lookup versions (borrowed from Allegro) was quite large: 20-50%,
depending on the usage. Every stroke calls sin() and cos() once, and
arcs can call them several times each.

Ben