[cairo] cairo-egl using libepoxy

[Alexander Larsson]

Given recent reports that cairo-egl performance is somewhat decent, i'm
interested in re-evaluating using it in Gtk+ in some cases. However, the
current backend uses either GLX or EGL and links directly to the backing
library, which is a non-started for Gtk+ which wants to ship a single
library that supports both X11 (GLX) and wayland (EGL).

The recent GL support in Gtk+ handles this by using libepoxy:
https://github.com/anholt/libepoxy

This is a very nice wrapper for GL that dlopens either of the backends
and allows you to write very nice generic code using the standard gl
function names which gets retargeted to the right backing library
automatically.

Whats the chances of switching cairo to using this library too?