[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 #9 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Created attachment 35367
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35367&action=edit
Draft patch