...even if they implement PPCallbacks, so filtering them out in
HandleTranslationUnit was ineffective.

Change-Id: I9df8103a50739f3176e6d63accfd0334da7faa9a
Reviewed-on: https://gerrit.libreoffice.org/43575Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>