Enable fontconfig fontmgr in public.bzl.

This enables the fontconfig font manager and tests it on unix like
platforms.

Change-Id: Ic0c2ad842e5f67fe50d100752d0eb239659d58e1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/203466
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
1 file changed