[Bug target/80782] Configure options to use llvm/clang assembler on Mac

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80782

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to René J.V. Bertin from comment #7)
> (In reply to Jonathan Wakely from comment #6)
> 
> > I assume something like --with-as=llvm-as doesn't work.
> 
> Nope.

What GCC version did you try?  6.x or 7.x?  There seems to be code to support
llvm-as in GCC 7.1.0 as shown in comment #8.