The string returned by object_property_get_str() is dynamically allocated.

Fixes: 3c4e9baaSigned-off-by: NGreg Kurz <groug@kaod.org>
Message-Id: <152231460685.69730.14860451936216690693.stgit@bahia.lan>
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NCornelia Huck <cohuck@redhat.com>