community/py3-xcffib: new aport, community/py3-cairocffi: add dep on py3-xcffib

https://github.com/tych0/xcffib Drop-in replacement for xpyb based on cffi

Allowed by Ariadne to go straight to community (will be needed for py3-cairocffi to be built against this)

The patch is modified from upstream commit 18310bc5e07ebe3f51a5a1d1b2597aaa39036c81 to fix pytest skipping a lot of tests

Also made py3-cairocffi depend on py3-xcffib (in order to build Qtile)