Cairo Remove old backends

[Brian Inglis]

Are any of these required by any graphics or desktop packages?

https://gitlab.freedesktop.org/cairo/cairo/-/merge_requests/285

Qt: depends on Qt 4, EOL in 2015
Cogl: depends on Cogl, unmaintained since 2016
OpenVG
BeOS: unsupported by Meson
OS/2: unsupported by Meson, last known built for Cairo 1.12 (2006)
DirectFB
DRM: science experiment, broken for at least 10 years

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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