It makes no sense to insist on a random type, only to reinterpret_cast
it everywhere. An opaque void fits the case perfectly.
Change-Id: If945b1c59d98c5f561350db649f29fe8036e7cdb
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/186982
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>