Dropping DirectFB backend from GTK 3

[Benjamin Otte <otte gnome org>]

Hey,

This is a notice that I intend to drop the DirectFB backend from GDK
3. It hasn't compiled for weeks now and I haven't heard from anyone
saying he'd look at it. More than that, people I asked about it have
told me that it's basically broken since 2.18, which is almost a year
ago. So it seems that backend is practically unmaintained and broken.

So rather than sending the wrong message about GTK supporting
something, I will get rid of it now that we break stuff anyway.

Benjamin