[Bug preprocessor/67551] Preprocessor generates non-ISO line directives

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67551

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
You can also use -P to get rid of the line markers from the processor output
which avoids your warning.