[clang] [clang] add x86_64 baremetal triple include search paths (PR #183453)

[Petr Hosek via cfe-commits]

petrhosek wrote:

> My understanding is that some of the headers in the resource directory want to be able to `#include_next` standard C headers, so the resource dir has to come before the c library's dirs.
> 
> Given there are other platforms which are working with the original order, I would suggest changing it back, but I'm not fully an expert on the expected order.

@lenary's summary is correct, can you please revert changes to `AddClangSystemIncludeArgs`?

https://github.com/llvm/llvm-project/pull/183453