Lots and lots of preparation led to this moment - when nothing
apparent changes for users! Woo!
But seriously, having the extra dependency is a minor annoyance, and
in the big picture I think the libgsystem idea was wrong - we need to
land things in GLib, and use git submodules for API-unstable or
Linux-specific sharing. For a lot of OSTree, the libgsystem `GFile*`
orientation was also wrong, we really want fd-relative.
Closes: #444
Approved by: jlebon
Jonathan Lebon
Colin Walters
Alexander Larsson
Giuseppe Scrivano