The existing implementation was completely incorrect (despite the fix in
commit 566e64a66) — it always compared GVariants by pointer, rather than
by value.
Reimplement it to compare them by value where possible, depending on
their type. The core of this implementation is g_variant_compare(). See
the documentation and tests for further details of the new sort order.
This adds documentation and tests.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://bugzilla.gnome.org/show_bug.cgi?id=795735