Hide warning spam from collada2gltf

Change-Id: Id772a8f4ca9f46f8a36dede759495e06c8e43732
Reviewed-on: https://gerrit.libreoffice.org/11343
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>