[llvm] [llvm][Support][Windows] Avoid crash calling remove_directories() (PR #118677)

[Dmitry Vasilyev via llvm-commits]

slydiman wrote:

std::filesystem::remove_all() works. But it uses std::filesystem::path as the argument. std::filesystem::path uses char on POSIX, wchar_t on Windows. So some custom code is still necessary. But remove_directories() may be simplified and unified very much for both POSIX and Windows. I will try to prepare such PR.

https://github.com/llvm/llvm-project/pull/118677