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

[howarth.at.gcc at gmail dot com]

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

--- Comment #33 from Jack Howarth <howarth.at.gcc at gmail dot com> ---
Alternative fix posted at
https://gcc.gnu.org/ml/gcc-patches/2016-11/msg01366.html