Merge branch 'warn-5.8' into master

Michal Kubecek:

Maciej ┼╗enczykowski recently cleaned up many "unused parameter" compiler
warnings but some new occurences appeared since (mostly in netlink code).

This series gets rid of all currently found "unused parameter" warnings and
also one zero length array access warning (gcc10). There are still some
compiler warnings left (signed/unsigned comparison and missing struct field
initializers); these will be handled in next cycle as the fixes are more
intrusive.

This series should not affect resulting code; checked by comparing
resulting binary against unpatched source.