[Bug other/79885] fix-includes does not honor the value passed to --with-build-sysroot=, looks for /usr/include instead of looking within the SDK

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79885

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Jeremy Huddleston Sequoia from comment #1)
> And note that I'm not using --with-sysroot because I don't want this to
> affect the compiler installed by 'make install', just what is used to build
> gcc itself.

You could have used --prefix instead.

I suspect darwin is different for native builds in that the sysroot is always
/.