and teach the idl compiler how to ignore the TypeWhichId<T1> part
of the define

Change-Id: I030f54080924d51e9f0ac09b19e14106648024db
Reviewed-on: https://gerrit.libreoffice.org/46849Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>