test-keyval: fix leaks

Spotted by ASAN.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170503223846.6559-2-marcandre.lureau@redhat.com>
Reviewed-by: Eric blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
