[bug#38376] [PATCH] gnu: clang: Fix search path detection with --sysroot.

[Mathieu Othacehe]

Hello Carl,

> Please do let me know if there’s anything amiss in the patch as it stands 
> right now!

Sorry for the delay! Well in the current form we end up with 4 big
patches to clang + 2 that are missing for clang-8 and clang-9.

This makes 6 patches, it will keep increasing. So maintaing those
patches will be very hard. I'd like to find another way to proceed.

Could we instead patch "clang-from-llvm" procedure to fix sysroot
support?

Mathieu