...new with Clang trunk 13. As a rule of thumb, this change adds explicit
cast-to-void silencing in those .cxx that already contained other such silencing
casts and adds wholesale #pragma clang diagnostic ignored in all others.
Change-Id: I1884496ee1aa81aaf3c8b3533534a4b69b185e9e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/116660
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
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