[Bug sanitizer/78267] [7 Regression] libsanitizer breaks bootstrap on x86_64-apple-darwin16 at r241977

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78267

--- Comment #21 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> Created attachment 40012 [details]
> Untested fix 2.

Bootstrap completed successfully with this patch.