[Bug other/70268] add option -ffile-prefix-map to map one directory name (old) to another (new) in __FILE__, __BASE_FILE__and __builtin_FILE()

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70268

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
IMHO it doesn't make sense to prune system header paths here and having them 
is desired.