We check that all members of the QLit list are also in the QList.  We
neglect to check the other direction.  Fix that.

While there, use QLIST_FOREACH_ENTRY() to simplify the code and break
the loop on the first mismatch.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170825105913.4060-13-marcandre.lureau@redhat.com>
[Commit message improved]
Signed-off-by: Markus Armbruster <armbru@redhat.com>