[Bug libstdc++/50871] libstdc++ should be built with -Wpedantic and/or -Wsystem-headers

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50871

--- Comment #19 from Sam James <sjames at gcc dot gnu.org> ---
FTR:
* r15-3714-gd3a7302ec5985a
* r15-3859-g63a598deb0c9fc