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

[Liviu Ionescu via cfe-commits]

ilg-ul wrote:

The ppc64 build failed with:

```
RUN: at line 186: mkdir -pv /home/powerllvm/powerllvm_env/aix-ppc64/clang-ppc64-aix/build/tools/clang/test/Driver/Output/darwin-header-search-libcxx.cpp.tmp/install/bin
+ mkdir -pv /home/powerllvm/powerllvm_env/aix-ppc64/clang-ppc64-aix/build/tools/clang/test/Driver/Output/darwin-header-search-libcxx.cpp.tmp/install/bin
mkdir: illegal option -- v
Usage: mkdir [-p] [-e] [-m mode] Directory ... 
```

How can I fix the test now?


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