[libcxx-commits] [libcxx] [libcxx] Use `aligned_alloc` for testing instead of `posix_memalign` (PR #101748)

[Joseph Huber via libcxx-commits]

jhuber6 wrote:

> There is no guarantee that a C library provides `aligned_alloc` before C++17. Is there a reason `posix_memalign` can't be provided?

I added a check for `-std=c++17` in the test suite since it's standardized since then and should be used instead.

https://github.com/llvm/llvm-project/pull/101748