[clang] [clang][driver] Add \<executable\>/../include/c++/v1 to include path on Darwin (PR #70817)

[Liviu Ionescu via cfe-commits]

ilg-ul wrote:

I pushed a new test that copies `clang` to a local `install` folder, to avoid creating folders in the build location.

The Linux build passed.

Any other comments?



https://github.com/llvm/llvm-project/pull/70817