[Bug c/122796] assert/macros from a system-header is incorrectly supressing a fallthrough warning

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122796

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note -Wsystem-headers will cause the warning to show up but that is just a
workaround (some system headers are not designed to be warning free).