[clang] [clang][Driver] Fix libc++ include path on FreeBSD (PR #212725)

[Brad Smith via cfe-commits]

brad0 wrote:

> Seems so, yes. However, I'd rather not do so myself: if this has gone unnoticed for quite some time, it's a strong indication of yet another community that either keeps patches to themselves or doesn't care about upstream. I had to do this on FreeBSD and NetBSD which I needed as reference for my GCC work, but have no OpenBSD test systems so far. Familiarizing yourself with the OS, package management, and trying to get LLVM to even build takes quite some time, unfortunately.

Or just does not care / hasn't been an issue using libc++ like this. There are no patches.

I can do the patch for OpenBSD.

https://github.com/llvm/llvm-project/pull/212725