[cairo] Sub-pixel Font Filtering in 1.10

[Brandon Wright]

I'm curious to know whether anyone has thought about including proper
support for sub-pixel font filtering in 1.10
(https://bugs.freedesktop.org/show_bug.cgi?id=10301).

Almost every distribution now includes patches to provide this in one
form or another, and Qt has had it since version 4.2.

Lance Hepler's patch
(http://lists.freedesktop.org/archives/cairo/2009-February/016494.html)
doesn't require any more external support than cairo needs now, and
this is the same approach Qt has taken.

It's kind of disconcerting to see all the different ways and old
patches that the distributions use to get this functionality. It's
been a few years since various patches and such began to spring up,
and it would really be nice to have this support in cairo proper. Keep
in mind that this really isn't about a developer sub-pixel API, but
rather support for a highly-desired user-configurable font feature.