the upstream gitlab server seems fairly flakey when accessed
from github ci :-/
In addition, the official github mirror over at
https://github.com/freetype/freetype is stale :-/
This is primarily for macos where the default freetype
installation is unable to render color emoji, but should also
help make things more consistent across the various platforms.
It's a little bit awkward on linux because the font-loader crate
pulls in the now-conflicting servo-font* crates. I've disabled
font-loader on linux systems; it's just calling fontconfig under
the covers anyway.
