[Bug c/85995] GCC defines __STDC__ and __STDC_VERSION__ even when used with options that break C conformance

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85995

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I guess that would break way more code than the current state (or force people
to use -std=cXX over -std=gnuXX).