[Bug target/90379] Gcc 9.1 fails "make check" on linux due to missing MacOS-specific header file

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90379

--- Comment #6 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Jürgen Reuter from comment #5)
> I am seeing the same issue on Darwin 18.5.0 (macOSX 10.4.4) with XCode 10.2.

Yeah, likewise, I'm looking at my Darwin18 system right now.