Use system fonts on Android (and maybe iOS too)

Submitted by Sebastian Dröge (slomo)

Description

+++ This bug was initially created as a clone of Bug 755375 +++

Quoting Nicolas there:

To be fair, in some project I just replaced that to point to Android font
directory (with manually written fontconfig index) and that work fine (and was
consistent with other apps). I never had the time to write a proper patch, but
it should not be hard.

Version: 1.5.90