[Bug c++/65801] [5/6 Regression] Allow -Wno-narrowing to silence stricter C++11 narrowing rules

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65801

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Well, at the time I think we agreed that we wanted to be strict at least about
enums... Otherwise, yes, we can do that plus setting ok = true in that case
too, thus collapsing the last two ifs (+ reverting the docs change and
adjusting the testsuite).