Add cairo-1.12.2

Needed for an upcoming fix to eclipse.

Signed-off-by: Shea Levy <shea@shealevy.com>
eclipses: use older cairo

In #167, Marc Weber reported that eclipse crashes after selecting a
workspace with the current nixpkgs cairo. This has the same functional
change as #167, but IMO the implementation is cleaner.

Fixes #167

Signed-off-by: Shea Levy <shea@shealevy.com>