[Bug c/91432] gcc -Wimplicit-fallthrough does not warn when fallthrough to break;

[joe at perches dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91432

--- Comment #7 from Joe Perches <joe at perches dot com> ---
What could be useful is to add yet another --extra-strict-fallthrough warning
flag that would make it possible for these cases to have a warning.