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

[Liviu Ionescu via cfe-commits]

ilg-ul wrote:

@Endilll, @AaronBallman, @bjope, @mstorsjo, this is a cleanup of a previous PR (#68091) where you contributed.

Could you take a second look?

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