[Bug target/81763] Issues with BMI on 32bit x86 apps on GCC 7.1+

[mike at fireburn dot co.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81763

--- Comment #10 from Mike Lothian <mike at fireburn dot co.uk> ---
Unfortunately it also depends on LLVM not just Mesa which makes it a much
bigger target for figuring this out