qobject: Let qobject_from_jsonf() fail instead of abort

qobject_from_jsonf() aborts on error, unlike qobject_from_jsonv(),
which returns null.  Since all remaining users of qobject_from_jsonf()
cope fine with null, change it to return null.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180703085358.13941-30-armbru@redhat.com>
1 file changed